diff --git a/README.md b/README.md
index 5bba1ae..4368a56 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,54 @@
 
 The goal of this Plugin is to ease the pain of dealing with relations in Shopware.
 
+## Shopware native
+
+Before explaining the solution in this Plugin, please be aware that there is a Shopware native way in the Sync-API
+to archive the same result. For example to assign a new category, you can send the following HTTP request:
+
+```http request
+POST /api/_action/sync
+Content-Type: application/json
+
+{
+    "change-category": {
+        "entity": "product",
+        "action": "upsert",
+        "payload": [
+            {
+                "id": "<the product id>",
+                "categories": [
+                    {"id": "<the new category id 1>"}
+                    {"id": "<the new category id 2>"}
+                ]
+            }
+        ]
+    },
+    "delete-obsolete": {
+        "entity": "product_category",
+        "action": "delete",
+        "criteria": [
+            {
+                "type": "equals",
+                "field": "productId",
+                "value": "<the product id>"
+            },
+            {
+                "type": "not",
+                "operator": "and",
+                "queries": [
+                    {
+                        "type": "equalsAny",
+                        "field": "categoryId",
+                        "value": ["<the new category id 1>", "<the new category id 2>"]
+                    }
+                ]
+            }
+        ]
+    }
+}
+```
+
 ## Quick start
 
 After installing the Plugin, you can enable automatic relation cleanup in
diff --git a/composer.json b/composer.json
index 59c2fa3..254ab8a 100644
--- a/composer.json
+++ b/composer.json
@@ -7,6 +7,7 @@
         "shopware/core": "~6.6.4"
     },
     "require-dev": {
+        "de-swebhosting-shopware-plugin/smart-relation-sync-test-plugin": "1.0.0",
         "de-swebhosting/php-codestyle": "^5.4",
         "ergebnis/composer-normalize": "^2.45",
         "friendsofphp/php-cs-fixer": "^3.66",
@@ -19,6 +20,12 @@
         "shopware/dev-tools": "^1.5",
         "symplify/phpstan-rules": "^14.4"
     },
+    "repositories": {
+        "SmartRelationSyncTestPlugin": {
+            "type": "path",
+            "url": "./tests/Fixtures/SmartRelationSyncTestPlugin"
+        }
+    },
     "autoload": {
         "psr-4": {
             "Swh\\SmartRelationSync\\": "src/"
@@ -26,7 +33,8 @@
     },
     "autoload-dev": {
         "psr-4": {
-            "Swh\\SmartRelationSync\\Tests\\": "tests/"
+            "Swh\\SmartRelationSync\\Tests\\Compatibility\\": "tests/Compatibility/",
+            "Swh\\SmartRelationSync\\Tests\\Functional\\": "tests/Functional/"
         }
     },
     "config": {
diff --git a/phpstan.neon b/phpstan.neon
index 6de7978..01ae162 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -28,6 +28,19 @@ parameters:
         consoleApplicationLoader: tests/StaticAnalyze/PHPStan/console-application.php
     type_perfect:
         no_mixed: true
+    ignoreErrors:
+        - identifier: class.extendsInternalClass
+        - identifier: classConstant.internalClass
+        - identifier: method.internal
+        - identifier: method.internalClass
+        - identifier: method.internalInterface
+        - identifier: new.internalClass
+        - identifier: parameter.internalClass
+        - identifier: parameter.internalInterface
+        - identifier: property.internalClass
+        - identifier: property.internalInterface
+        - identifier: return.internalClass
+        - identifier: staticMethod.internal
 
 services:
     - # register the class, so we can decorate it, but don't tag it as a rule, so only our decorator is used by PHPStan
diff --git a/src/ApiDefinition/EntitySchemaGeneratorDecorator.php b/src/ApiDefinition/EntitySchemaGeneratorDecorator.php
index e5c8537..9eb6995 100644
--- a/src/ApiDefinition/EntitySchemaGeneratorDecorator.php
+++ b/src/ApiDefinition/EntitySchemaGeneratorDecorator.php
@@ -11,10 +11,9 @@
 use Shopware\Core\Framework\Api\Context\AdminApiSource;
 use Shopware\Core\Framework\DataAbstractionLayer\EntityDefinition;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\Field;
-use Shopware\Core\Framework\DataAbstractionLayer\Field\ManyToManyAssociationField;
-use Shopware\Core\Framework\DataAbstractionLayer\Field\OneToManyAssociationField;
 use Shopware\Core\System\SalesChannel\Entity\SalesChannelDefinitionInterface;
 use Swh\SmartRelationSync\DataAbstractionLayer\WriteCommandExtractorDecorator;
+use Swh\SmartRelationSync\ValueObject\RelevantField;
 
 /**
  * @internal
@@ -66,7 +65,7 @@ public function getSchema(array $definitions): array
             $entityProperties = $schema[$entity]['properties'];
 
             $relevantFields = $definition->getFields()
-                ->filter(fn(Field $field) => $this->isRelevantField($field));
+                ->filter(static fn(Field $field) => RelevantField::isRelevant($field));
 
             foreach ($relevantFields as $field) {
                 if (!array_key_exists($field->getPropertyName(), $entityProperties)) {
@@ -88,12 +87,4 @@ public function supports(string $format, string $api): bool
     {
         return $this->decorated->supports($format, $api);
     }
-
-    /**
-     * @phpstan-assert-if-true ManyToManyAssociationField|OneToManyAssociationField $field
-     */
-    private function isRelevantField(Field $field): bool
-    {
-        return WriteCommandExtractorDecorator::isRelevantField($field);
-    }
 }
diff --git a/src/ApiDefinition/OpenApiDefinitionSchemaBuilderDecorator.php b/src/ApiDefinition/OpenApiDefinitionSchemaBuilderDecorator.php
index 0655e6f..01b56f2 100644
--- a/src/ApiDefinition/OpenApiDefinitionSchemaBuilderDecorator.php
+++ b/src/ApiDefinition/OpenApiDefinitionSchemaBuilderDecorator.php
@@ -6,6 +6,7 @@
 
 use OpenApi\Annotations\Property;
 use OpenApi\Annotations\Schema;
+use RuntimeException;
 use Shopware\Core\Framework\Api\ApiDefinition\DefinitionService;
 use Shopware\Core\Framework\Api\ApiDefinition\Generator\OpenApi\OpenApiDefinitionSchemaBuilder;
 use Shopware\Core\Framework\Api\Context\AdminApiSource;
@@ -13,10 +14,10 @@
 use Shopware\Core\Framework\DataAbstractionLayer\EntityDefinition;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\Field;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\ApiAware;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\Extension;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\IgnoreInOpenapiSchema;
-use Shopware\Core\Framework\DataAbstractionLayer\Field\ManyToManyAssociationField;
-use Shopware\Core\Framework\DataAbstractionLayer\Field\OneToManyAssociationField;
 use Swh\SmartRelationSync\DataAbstractionLayer\WriteCommandExtractorDecorator;
+use Swh\SmartRelationSync\ValueObject\RelevantField;
 use Symfony\Component\Serializer\NameConverter\CamelCaseToSnakeCaseNameConverter;
 
 class OpenApiDefinitionSchemaBuilderDecorator extends OpenApiDefinitionSchemaBuilder
@@ -53,7 +54,7 @@ public function getSchemaByDefinition(
         }
 
         $relevantFields = $definition->getFields()
-            ->filter(fn(Field $field) => $this->isRelevantField($field));
+            ->filter(static fn(Field $field) => RelevantField::isRelevant($field));
 
         foreach ($relevantFields as $field) {
             if (!$this->shouldFieldBeIncluded($field, $forSalesChannel)) {
@@ -68,14 +69,48 @@ public function getSchemaByDefinition(
                 'writeOnly' => true,
             ]);
 
-            foreach ($relevantSchemas as $schema) {
-                $schema->properties[] = $property;
-            }
+            match ($field->is(Extension::class)) {
+                true => $this->addExtensionToSchemas($relevantSchemas, $property),
+                false => $this->addPropertyToSchemas($relevantSchemas, $property),
+            };
         }
 
         return $schemas;
     }
 
+    /**
+     * @param Schema[] $schemas
+     */
+    private function addExtensionToSchemas(array $schemas, Property $property): void
+    {
+        foreach ($schemas as $schema) {
+            $extensionSchema = $this->getExtensionSchema($schema);
+
+            $extensionSchema->properties[] = $property;
+        }
+    }
+
+    /**
+     * @param Schema[] $schemas
+     */
+    private function addPropertyToSchemas(array $schemas, Property $property): void
+    {
+        foreach ($schemas as $schema) {
+            $schema->properties[] = $property;
+        }
+    }
+
+    private function getExtensionSchema(Schema $schema): Schema
+    {
+        foreach ($schema->properties as $property) {
+            if ($property->property === 'extensions') {
+                return $property;
+            }
+        }
+
+        throw new RuntimeException('extensions property not found');
+    }
+
     /**
      * @param Schema[] $schemas
      *
@@ -108,14 +143,6 @@ private function getRelevantSchemas(array $schemas, EntityDefinition $definition
         return $relevantSchemas;
     }
 
-    /**
-     * @phpstan-assert-if-true ManyToManyAssociationField|OneToManyAssociationField $field
-     */
-    private function isRelevantField(Field $field): bool
-    {
-        return WriteCommandExtractorDecorator::isRelevantField($field);
-    }
-
     private function shouldFieldBeIncluded(Field $field, bool $forSalesChannel): bool
     {
         if ($field->getPropertyName() === 'translations'
diff --git a/src/DataAbstractionLayer/WriteCommandExtractorDecorator.php b/src/DataAbstractionLayer/WriteCommandExtractorDecorator.php
index 2f6366b..60a69c4 100644
--- a/src/DataAbstractionLayer/WriteCommandExtractorDecorator.php
+++ b/src/DataAbstractionLayer/WriteCommandExtractorDecorator.php
@@ -9,6 +9,7 @@
 use Shopware\Core\Framework\DataAbstractionLayer\EntityDefinition;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\Field;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\FkField;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\Extension;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\ManyToManyAssociationField;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\ManyToOneAssociationField;
 use Shopware\Core\Framework\DataAbstractionLayer\Field\OneToManyAssociationField;
@@ -17,6 +18,7 @@
 use Shopware\Core\Framework\DataAbstractionLayer\Version\VersionDefinition;
 use Shopware\Core\Framework\DataAbstractionLayer\Write\WriteCommandExtractor;
 use Shopware\Core\Framework\DataAbstractionLayer\Write\WriteParameterBag;
+use Swh\SmartRelationSync\ValueObject\RelevantField;
 
 final class WriteCommandExtractorDecorator extends WriteCommandExtractor
 {
@@ -31,15 +33,6 @@ public static function getCleanupEnableFieldName(Field $field): string
         return sprintf('%sCleanupRelations', $field->getPropertyName());
     }
 
-    /**
-     * @phpstan-assert-if-true ManyToManyAssociationField|OneToManyAssociationField $field
-     */
-    public static function isRelevantField(Field $field): bool
-    {
-        return $field instanceof ManyToManyAssociationField
-            || $field instanceof OneToManyAssociationField;
-    }
-
     /**
      * @param array<mixed, mixed> $rawData
      */
@@ -226,6 +219,65 @@ private function getPrimaryKeyFields(EntityDefinition $reference): array
         return $fields;
     }
 
+    /**
+     * @param array<mixed, mixed> $rawData
+     *
+     * @return array<mixed, mixed>
+     */
+    private function getRelevantRawData(Field $field, array $rawData): array
+    {
+        if (!$field->is(Extension::class)) {
+            return $rawData;
+        }
+
+        $propertyName = $field->getPropertyName();
+
+        if (isset($rawData[$propertyName])) {
+            return $rawData;
+        }
+
+        if (
+            !isset($rawData['extensions'])
+            || !is_array($rawData['extensions'])
+            || !isset($rawData['extensions'][$propertyName])) {
+            return $rawData;
+        }
+
+        return $rawData['extensions'];
+    }
+
+    /**
+     * @param array<mixed, mixed> $rawData
+     */
+    private function registerFieldForCleanup(
+        RelevantField $relevantField,
+        array $rawData,
+    ): void {
+        $field = $relevantField->field;
+
+        $fieldData = $rawData[$field->getPropertyName()] ?? null;
+
+        if (!is_array($fieldData)) {
+            return;
+        }
+
+        $cleanupEnableField = $this->getCleanupEnableFieldName($field);
+
+        if (!array_key_exists($cleanupEnableField, $rawData)) {
+            return;
+        }
+
+        $cleanupEnabled = is_bool($rawData[$cleanupEnableField]) && $rawData[$cleanupEnableField];
+
+        unset($rawData[$cleanupEnableField]);
+
+        if (!$cleanupEnabled) {
+            return;
+        }
+
+        $this->registerRelationsForField($relevantField, $fieldData);
+    }
+
     /**
      * @param array<mixed, mixed> $rawData
      */
@@ -247,43 +299,28 @@ private function registerRelations(array $rawData, WriteParameterBag $parameters
         $primaryKeys = $this->filterVersionFields($primaryKeys, $definition);
 
         foreach ($definition->getFields() as $field) {
-            if (!self::isRelevantField($field)) {
-                continue;
-            }
-
-            $cleanupEnableField = $this->getCleanupEnableFieldName($field);
+            $relevantField = RelevantField::create($field, $primaryKeys);
 
-            if (!array_key_exists($cleanupEnableField, $rawData)) {
+            if ($relevantField === null) {
                 continue;
             }
 
-            $cleanupEnabled = is_bool($rawData[$cleanupEnableField]) && $rawData[$cleanupEnableField];
-
-            unset($rawData[$cleanupEnableField]);
-
-            if (!$cleanupEnabled) {
-                continue; // @codeCoverageIgnore
-            }
-
-            $fieldData = $rawData[$field->getPropertyName()] ?? null;
+            $rawData = $this->getRelevantRawData($field, $rawData);
 
-            if (!is_array($fieldData)) {
-                continue;
-            }
-
-            $this->registerRelationsForField($field, $primaryKeys, $fieldData);
+            $this->registerFieldForCleanup($relevantField, $rawData);
         }
     }
 
     /**
-     * @param non-empty-array<non-empty-string, non-empty-string> $parentPrimaryKey
      * @param array<mixed, mixed> $fieldData
      */
     private function registerRelationsForField(
-        ManyToManyAssociationField|OneToManyAssociationField $field,
-        array $parentPrimaryKey,
+        RelevantField $relevantField,
         array $fieldData,
     ): void {
+        $field = $relevantField->field;
+        $parentPrimaryKey = $relevantField->parentPrimaryKey;
+
         $reference = $field->getReferenceDefinition();
 
         $cleanupRelationData = match ($field instanceof OneToManyAssociationField) {
diff --git a/src/ValueObject/RelevantField.php b/src/ValueObject/RelevantField.php
new file mode 100644
index 0000000..b96660f
--- /dev/null
+++ b/src/ValueObject/RelevantField.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Swh\SmartRelationSync\ValueObject;
+
+use Shopware\Core\Framework\DataAbstractionLayer\Field\Field;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\ManyToManyAssociationField;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\OneToManyAssociationField;
+
+readonly class RelevantField
+{
+    /**
+     * @param non-empty-array<non-empty-string, non-empty-string> $parentPrimaryKey
+     */
+    public function __construct(
+        public ManyToManyAssociationField|OneToManyAssociationField $field,
+        public array $parentPrimaryKey,
+    ) {}
+
+    /**
+     * @param non-empty-array<non-empty-string, non-empty-string> $parentPrimaryKey
+     */
+    public static function create(Field $field, array $parentPrimaryKey): ?self
+    {
+        if (!self::isRelevant($field)) {
+            return null;
+        }
+
+        /** @var ManyToManyAssociationField|OneToManyAssociationField $field */
+        return new self($field, $parentPrimaryKey);
+    }
+
+    /**
+     * @phpstan-assert-if-true ManyToManyAssociationField|OneToManyAssociationField $field
+     */
+    public static function isRelevant(Field $field): bool
+    {
+        return $field instanceof ManyToManyAssociationField
+            || $field instanceof OneToManyAssociationField;
+    }
+}
diff --git a/tests/Fixtures/SmartRelationSyncTestPlugin/composer.json b/tests/Fixtures/SmartRelationSyncTestPlugin/composer.json
new file mode 100644
index 0000000..5a5fe5f
--- /dev/null
+++ b/tests/Fixtures/SmartRelationSyncTestPlugin/composer.json
@@ -0,0 +1,19 @@
+{
+    "name": "de-swebhosting-shopware-plugin/smart-relation-sync-test-plugin",
+    "description": "SmartRelationSync plugin test plugin",
+    "version": "1.0.0",
+    "license": "MIT",
+    "type": "shopware-platform-plugin",
+    "autoload": {
+        "psr-4": {
+            "Swh\\SmartRelationSyncTestPlugin\\": "src/"
+        }
+    },
+    "extra": {
+        "label": {
+            "de-DE": "SmartRelationSync Test",
+            "en-GB": "SmartRelationSync Test"
+        },
+        "shopware-plugin-class": "Swh\\SmartRelationSyncTestPlugin\\SmartRelationSyncTestPlugin"
+    }
+}
diff --git a/tests/Fixtures/SmartRelationSyncTestPlugin/src/Entity/PropertyGroupOptionExcludeDefinition.php b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Entity/PropertyGroupOptionExcludeDefinition.php
new file mode 100644
index 0000000..b471324
--- /dev/null
+++ b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Entity/PropertyGroupOptionExcludeDefinition.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Swh\SmartRelationSyncTestPlugin\Entity;
+
+use Shopware\Core\Content\Property\Aggregate\PropertyGroupOption\PropertyGroupOptionDefinition;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\FkField;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\PrimaryKey;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\Required;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\ManyToOneAssociationField;
+use Shopware\Core\Framework\DataAbstractionLayer\FieldCollection;
+use Shopware\Core\Framework\DataAbstractionLayer\MappingEntityDefinition;
+
+class PropertyGroupOptionExcludeDefinition extends MappingEntityDefinition
+{
+    final public const string ENTITY_NAME = 'property_group_option_exclude';
+
+    public function getEntityName(): string
+    {
+        return self::ENTITY_NAME;
+    }
+
+    protected function defineFields(): FieldCollection
+    {
+        return new FieldCollection([
+            (new FkField('property_group_option_id', 'optionId', PropertyGroupOptionDefinition::class))->addFlags(new PrimaryKey(), new Required()),
+            new ManyToOneAssociationField('option', 'property_group_option_id', PropertyGroupOptionDefinition::class, 'id', false),
+
+            (new FkField('property_group_option_exclude_id', 'excludedOptionId', PropertyGroupOptionDefinition::class))->addFlags(new PrimaryKey(), new Required()),
+            new ManyToOneAssociationField('excludedOption', 'property_group_option_exclude_id', PropertyGroupOptionDefinition::class, 'id', false),
+        ]);
+    }
+}
diff --git a/tests/Fixtures/SmartRelationSyncTestPlugin/src/Entity/PropertyGroupOptionExcludeExtension.php b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Entity/PropertyGroupOptionExcludeExtension.php
new file mode 100644
index 0000000..ba78bfc
--- /dev/null
+++ b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Entity/PropertyGroupOptionExcludeExtension.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Swh\SmartRelationSyncTestPlugin\Entity;
+
+use Shopware\Core\Content\Property\Aggregate\PropertyGroupOption\PropertyGroupOptionDefinition;
+use Shopware\Core\Framework\DataAbstractionLayer\EntityExtension;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\ApiAware;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\Flag\CascadeDelete;
+use Shopware\Core\Framework\DataAbstractionLayer\Field\ManyToManyAssociationField;
+use Shopware\Core\Framework\DataAbstractionLayer\FieldCollection;
+
+class PropertyGroupOptionExcludeExtension extends EntityExtension
+{
+    public const string EXTENSION_NAME = 'excludedOptions';
+
+    public function extendFields(FieldCollection $collection): void
+    {
+        $collection->add(
+            (new ManyToManyAssociationField(
+                self::EXTENSION_NAME,
+                PropertyGroupOptionDefinition::class,
+                PropertyGroupOptionExcludeDefinition::class,
+                'property_group_option_id',
+                'property_group_option_exclude_id',
+            )
+            )->addFlags(new ApiAware(), new CascadeDelete()),
+        );
+    }
+
+    public function getDefinitionClass(): string
+    {
+        return PropertyGroupOptionDefinition::class;
+    }
+}
diff --git a/tests/Fixtures/SmartRelationSyncTestPlugin/src/Migration/Migration1746808550ProductPropertyOptionGroupExclude.php b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Migration/Migration1746808550ProductPropertyOptionGroupExclude.php
new file mode 100644
index 0000000..9544822
--- /dev/null
+++ b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Migration/Migration1746808550ProductPropertyOptionGroupExclude.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Swh\SmartRelationSyncTestPlugin\Migration;
+
+use Doctrine\DBAL\Connection;
+use Shopware\Core\Framework\Migration\MigrationStep;
+
+class Migration1746808550ProductPropertyOptionGroupExclude extends MigrationStep
+{
+    public function getCreationTimestamp(): int
+    {
+        return 1746808550;
+    }
+
+    public function update(Connection $connection): void
+    {
+        $sql = <<<'SQL'
+            CREATE TABLE `property_group_option_exclude` (
+                `property_group_option_id` BINARY(16) NOT NULL,
+                `property_group_option_exclude_id` BINARY(16) NOT NULL,
+                PRIMARY KEY (`property_group_option_id`, `property_group_option_exclude_id`),
+                CONSTRAINT `fk.option_exclude.property_group_option_id`
+                    FOREIGN KEY (`property_group_option_id`) REFERENCES `property_group_option` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
+                CONSTRAINT `fk.option_exclude.property_group_option_exclude_id`
+                    FOREIGN KEY (`property_group_option_exclude_id`) REFERENCES `property_group_option` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
+            ) ENGINE = InnoDB DEFAULT CHARSET = utf8mb4 COLLATE = utf8mb4_unicode_ci;
+            SQL;
+
+        $connection->executeStatement($sql);
+    }
+}
diff --git a/tests/Fixtures/SmartRelationSyncTestPlugin/src/Resources/config/services.php b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Resources/config/services.php
new file mode 100644
index 0000000..efedcbf
--- /dev/null
+++ b/tests/Fixtures/SmartRelationSyncTestPlugin/src/Resources/config/services.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+use Swh\SmartRelationSyncTestPlugin\Entity\PropertyGroupOptionExcludeDefinition;
+use Swh\SmartRelationSyncTestPlugin\Entity\PropertyGroupOptionExcludeExtension;
+use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+
+return static function (ContainerConfigurator $containerConfigurator): void {
+    $services = $containerConfigurator->services()
+        ->defaults()
+        ->private()
+        ->autowire()
+        ->autoconfigure();
+
+    $services->set(PropertyGroupOptionExcludeDefinition::class);
+    $services->set(PropertyGroupOptionExcludeExtension::class);
+};
diff --git a/tests/Fixtures/SmartRelationSyncTestPlugin/src/SmartRelationSyncTestPlugin.php b/tests/Fixtures/SmartRelationSyncTestPlugin/src/SmartRelationSyncTestPlugin.php
new file mode 100644
index 0000000..e2f2664
--- /dev/null
+++ b/tests/Fixtures/SmartRelationSyncTestPlugin/src/SmartRelationSyncTestPlugin.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Swh\SmartRelationSyncTestPlugin;
+
+use Shopware\Core\Framework\Plugin;
+
+class SmartRelationSyncTestPlugin extends Plugin {}
diff --git a/tests/Functional/ApiDefinition/EntitySchemaGeneratorDecoratorTest.php b/tests/Functional/ApiDefinition/EntitySchemaGeneratorDecoratorTest.php
index 72699b5..f3ae284 100644
--- a/tests/Functional/ApiDefinition/EntitySchemaGeneratorDecoratorTest.php
+++ b/tests/Functional/ApiDefinition/EntitySchemaGeneratorDecoratorTest.php
@@ -31,9 +31,16 @@ public function testApiSchemaReturnsExpectedProperties(): void
         $json = json_decode($json, true);
 
         self::assertIsArray($json);
+
         self::assertIsArray($json['product']);
         self::assertIsArray($json['product']['properties']);
         self::assertIsArray($json['product']['properties']['categoriesCleanupRelations']);
         self::assertSame('boolean', $json['product']['properties']['categoriesCleanupRelations']['type']);
+
+        self::assertIsArray($json['property_group_option']);
+        self::assertIsArray($json['property_group_option']['properties']);
+        self::assertIsArray($json['property_group_option']['properties']['excludedOptions']);
+        self::assertIsArray($json['property_group_option']['properties']['excludedOptionsCleanupRelations']);
+        self::assertSame('boolean', $json['property_group_option']['properties']['excludedOptionsCleanupRelations']['type']);
     }
 }
diff --git a/tests/Functional/ApiDefinition/OpenApiDefinitionSchemaBuilderDecoratorTest.php b/tests/Functional/ApiDefinition/OpenApiDefinitionSchemaBuilderDecoratorTest.php
index f42b8d8..c7d259a 100644
--- a/tests/Functional/ApiDefinition/OpenApiDefinitionSchemaBuilderDecoratorTest.php
+++ b/tests/Functional/ApiDefinition/OpenApiDefinitionSchemaBuilderDecoratorTest.php
@@ -4,12 +4,15 @@
 
 namespace Swh\SmartRelationSync\Tests\Functional\ApiDefinition;
 
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
 use Shopware\Core\Framework\Api\ApiDefinition\DefinitionService;
 use Shopware\Core\Framework\Test\TestCaseBase\AdminFunctionalTestBehaviour;
+use Swh\SmartRelationSync\ApiDefinition\OpenApiDefinitionSchemaBuilderDecorator;
 use Symfony\Component\HttpFoundation\JsonResponse;
 
+#[CoversClass(OpenApiDefinitionSchemaBuilderDecorator::class)]
 class OpenApiDefinitionSchemaBuilderDecoratorTest extends TestCase
 {
     use AdminFunctionalTestBehaviour;
@@ -47,9 +50,24 @@ public function testApiSchemaReturnsExpectedProperties(string $type): void
         self::assertIsArray($json);
         self::assertIsArray($json['components']);
         self::assertIsArray($json['components']['schemas']);
-        self::assertIsArray($json['components']['schemas']['Product']);
-        self::assertIsArray($json['components']['schemas']['Product']['properties']);
-        self::assertIsArray($json['components']['schemas']['Product']['properties']['categoriesCleanupRelations']);
-        self::assertSame('boolean', $json['components']['schemas']['Product']['properties']['categoriesCleanupRelations']['type']);
+
+        $schemas = $json['components']['schemas'];
+
+        self::assertIsArray($schemas['Product']);
+        self::assertIsArray($schemas['Product']['properties']);
+        self::assertIsArray($schemas['Product']['properties']['categoriesCleanupRelations']);
+        self::assertSame('boolean', $schemas['Product']['properties']['categoriesCleanupRelations']['type']);
+
+        self::assertIsArray($schemas['PropertyGroupOption']);
+        self::assertIsArray($schemas['PropertyGroupOption']['properties']);
+        self::assertIsArray($schemas['PropertyGroupOption']['properties']['extensions']);
+
+        self::assertIsArray($schemas['PropertyGroupOption']['properties']['extensions']);
+        self::assertIsArray($schemas['PropertyGroupOption']['properties']['extensions']['properties']);
+
+        $extensions = $schemas['PropertyGroupOption']['properties']['extensions']['properties'];
+        self::assertIsArray($extensions['excludedOptions']);
+        self::assertIsArray($extensions['excludedOptionsCleanupRelations']);
+        self::assertSame('boolean', $extensions['excludedOptionsCleanupRelations']['type']);
     }
 }
diff --git a/tests/Functional/DataAbstractionLayer/AbstractEntityWriteSubscriberTestCase.php b/tests/Functional/DataAbstractionLayer/AbstractEntityWriteSubscriberTestCase.php
index 6592f10..4290ecf 100644
--- a/tests/Functional/DataAbstractionLayer/AbstractEntityWriteSubscriberTestCase.php
+++ b/tests/Functional/DataAbstractionLayer/AbstractEntityWriteSubscriberTestCase.php
@@ -4,15 +4,19 @@
 
 namespace Swh\SmartRelationSync\Tests\Functional\DataAbstractionLayer;
 
+use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
 use Shopware\Core\Content\Category\CategoryCollection;
 use Shopware\Core\Content\Product\ProductCollection;
 use Shopware\Core\Content\Product\ProductEntity;
+use Shopware\Core\Content\Property\Aggregate\PropertyGroupOption\PropertyGroupOptionCollection;
+use Shopware\Core\Content\Property\Aggregate\PropertyGroupOption\PropertyGroupOptionEntity;
 use Shopware\Core\Content\Test\Product\ProductBuilder;
 use Shopware\Core\Framework\Context;
 use Shopware\Core\Framework\DataAbstractionLayer\EntityRepository;
 use Shopware\Core\Framework\DataAbstractionLayer\Search\Criteria;
 use Shopware\Core\Framework\Test\TestCaseBase\IntegrationTestBehaviour;
+use Shopware\Core\Framework\Uuid\Uuid;
 use Swh\SmartRelationSync\Tests\Compatibility\IdsCollection;
 
 abstract class AbstractEntityWriteSubscriberTestCase extends TestCase
@@ -26,9 +30,10 @@ abstract class AbstractEntityWriteSubscriberTestCase extends TestCase
     private IdsCollection $ids;
 
     /**
+     * @param non-empty-string $entity
      * @param array<non-empty-string, mixed> $payload
      */
-    abstract protected function upsertProduct(array $payload): void;
+    abstract protected function upsertEntity(string $entity, array $payload): void;
 
     protected function setUp(): void
     {
@@ -36,6 +41,17 @@ protected function setUp(): void
         $this->ids = new IdsCollection();
     }
 
+    /**
+     * @return array<array{0: bool}>
+     */
+    public static function trueFalseDataProvider(): array
+    {
+        return [
+            [true],
+            [false],
+        ];
+    }
+
     public function testSyncManyToMany(): void
     {
         $builder = $this->createProductBuilder()
@@ -53,6 +69,43 @@ public function testSyncManyToMany(): void
         self::assertSame($this->ids->get('Test 2'), $categories?->first()?->getId());
     }
 
+    #[DataProvider('trueFalseDataProvider')]
+    public function testSyncManyToManyExtension(bool $useExtensionsProperty): void
+    {
+        $excludedOption1 = ['id' => Uuid::randomHex(), 'name' => 'Excluded option 1', 'group' => ['name' => 'Group 1']];
+        $this->upsertEntity('property_group_option', $excludedOption1);
+
+        $excludedOption2 = ['id' => Uuid::randomHex(), 'name' => 'Excluded option 2', 'group' => ['name' => 'Group 2']];
+        $this->upsertEntity('property_group_option', $excludedOption2);
+
+        $propertyGroup = $this->buildPropertyGroupData($useExtensionsProperty, $excludedOption1['id']);
+
+        $this->upsertEntity('property_group', $propertyGroup);
+
+        $optionData = $propertyGroup['options'][0];
+
+        match ($useExtensionsProperty) {
+            true => $optionData['extensions']['excludedOptions'][0]['id'] = $excludedOption2['id'],
+            false => $optionData['excludedOptions'][0]['id'] = $excludedOption2['id'],
+        };
+
+        $this->upsertEntity('property_group_option', $optionData);
+
+        $criteria = new Criteria([$optionData['id']]);
+        $criteria->addAssociation('excludedOptions');
+        $result = $this->getContainer()->get('property_group_option.repository')
+            ->search($criteria, $this->context)
+            ->first();
+
+        self::assertInstanceOf(PropertyGroupOptionEntity::class, $result);
+
+        $extension = $result->getExtension('excludedOptions');
+        self::assertInstanceOf(PropertyGroupOptionCollection::class, $extension);
+        self::assertCount(1, $extension);
+
+        self::assertSame($excludedOption2['id'], $extension->first()?->getId());
+    }
+
     public function testSyncManyToManyWithEmptyArray(): void
     {
         $builder = $this->createProductBuilder()
@@ -74,12 +127,12 @@ public function testSyncManyToManyWithoutCleanup(): void
         $builder = $this->createProductBuilder()
             ->category('Test 1');
 
-        $this->upsertProduct($builder->build());
+        $this->upsertEntity('product', $builder->build());
 
         $builder = $this->createProductBuilder()
             ->category('Test 2');
 
-        $this->upsertProduct($builder->build());
+        $this->upsertEntity('product', $builder->build());
 
         $categories = $this->loadCategories();
         self::assertCount(2, $categories ?? []);
@@ -128,6 +181,45 @@ protected function loadCategories(): ?CategoryCollection
         return $product->getCategories();
     }
 
+    /**
+     * @return array{
+     *     id: non-empty-string,
+     *     name: non-empty-string,
+     *     options: array{
+     *         0: array{
+     *             id: non-empty-string,
+     *             name: non-empty-string,
+     *             extensions?: array{excludedOptions: array{0: array{id: string}}, excludedOptionsCleanupRelations: bool},
+     *             excludedOptions?: array{0: array{id: string}},
+     *             excludedOptionsCleanupRelations?: bool,
+     *         }
+     *     }
+     * }
+     */
+    private function buildPropertyGroupData(bool $useExtensionsProperty, string $excludedOptionId): array
+    {
+        $extensionData = [
+            'excludedOptions' => [['id' => $excludedOptionId]],
+            'excludedOptionsCleanupRelations' => true,
+        ];
+
+        $optionData = [
+            'id' => Uuid::randomHex(),
+            'name' => 'Test option',
+        ];
+
+        match ($useExtensionsProperty) {
+            true => $optionData['extensions'] = $extensionData,
+            false => $optionData = array_merge($optionData, $extensionData),
+        };
+
+        return [
+            'id' => Uuid::randomHex(),
+            'name' => 'Test group',
+            'options' => [$optionData],
+        ];
+    }
+
     private function createProductBuilder(): ProductBuilder
     {
         return (new ProductBuilder($this->ids, self::PRODUCT_NUMBER))
@@ -163,6 +255,6 @@ private function upsertProductWithRelationCleanup(array $payload): void
         $payload['pricesCleanupRelations'] = true;
         $payload['categoriesCleanupRelations'] = true;
 
-        $this->upsertProduct($payload);
+        $this->upsertEntity('product', $payload);
     }
 }
diff --git a/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberApiTest.php b/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberApiTest.php
index 793b5bb..49650b8 100644
--- a/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberApiTest.php
+++ b/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberApiTest.php
@@ -10,14 +10,14 @@ class EntityWriteSubscriberApiTest extends AbstractEntityWriteSubscriberTestCase
 {
     use AdminApiTestBehaviour;
 
-    protected function upsertProduct(array $payload): void
+    protected function upsertEntity(string $entity, array $payload): void
     {
         $this->getBrowser()->jsonRequest(
             'POST',
             '/api/_action/sync',
             [
                 'write-product' => [
-                    'entity' => 'product',
+                    'entity' => $entity,
                     'action' => 'upsert',
                     'payload' => [$payload],
                 ],
diff --git a/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberDalTest.php b/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberDalTest.php
index 0720fdd..783c523 100644
--- a/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberDalTest.php
+++ b/tests/Functional/DataAbstractionLayer/EntityWriteSubscriberDalTest.php
@@ -4,11 +4,16 @@
 
 namespace Swh\SmartRelationSync\Tests\Functional\DataAbstractionLayer;
 
+use Shopware\Core\Framework\DataAbstractionLayer\EntityRepository;
+
 class EntityWriteSubscriberDalTest extends AbstractEntityWriteSubscriberTestCase
 {
-    protected function upsertProduct(array $payload): void
+    protected function upsertEntity(string $entity, array $payload): void
     {
-        $this->getContainer()->get('product.repository')
-            ->upsert([$payload], $this->context);
+        $repository = $this->getContainer()->get($entity . '.repository');
+
+        assert($repository instanceof EntityRepository);
+
+        $repository->upsert([$payload], $this->context);
     }
 }
diff --git a/tests/TestBootstrap.php b/tests/TestBootstrap.php
index ac7457f..2ffb362 100644
--- a/tests/TestBootstrap.php
+++ b/tests/TestBootstrap.php
@@ -9,5 +9,6 @@
 (new TestBootstrapper())
     ->setClassLoader($loader)
     ->setPlatformEmbedded(true)
+    ->addActivePlugins('SmartRelationSyncTestPlugin')
     ->addCallingPlugin(__DIR__ . '/../composer.json')
     ->bootstrap();