diff --git a/test/compatibility-suites/openapi/response-body-schema.test.ts b/test/compatibility-suites/openapi/response-body-schema.test.ts
index 57e87bf..d10f96a 100644
--- a/test/compatibility-suites/openapi/response-body-schema.test.ts
+++ b/test/compatibility-suites/openapi/response-body-schema.test.ts
@@ -1636,3 +1636,4 @@ describe('Openapi3 ResponseBody.Schema ', () => {
 describe('Openapi31 ResponseBody.Schema', () => {
   runCommonResponseSchema31Tests(SUITE_ID, RESPONSE_SCHEMA_PATH)
 })
+
diff --git a/test/compatibility-suites/openapi/templates/reference-object-31.template.ts b/test/compatibility-suites/openapi/templates/reference-object-31.template.ts
index c7b56e5..de08d97 100644
--- a/test/compatibility-suites/openapi/templates/reference-object-31.template.ts
+++ b/test/compatibility-suites/openapi/templates/reference-object-31.template.ts
@@ -58,7 +58,7 @@ export function runReferenceObjectTests(suiteId: string, refPath: JsonPath, comp
 
   test(`Change referenced ${overridenField} when overridden exists`, async () => {
     const testId = `change-referenced-${overridenField}-when-overridden-exists`
-    const result = await compareFiles(suiteId, testId)
-    expect(result.length).toEqual(0)
+    const diffs = await compareFiles(suiteId, testId)
+    expect(diffs).toBeEmpty()
   })
 }
diff --git a/test/compatibility-suites/openapi/templates/response-schema31.ts b/test/compatibility-suites/openapi/templates/response-schema31.ts
index 6f2a474..17a006f 100644
--- a/test/compatibility-suites/openapi/templates/response-schema31.ts
+++ b/test/compatibility-suites/openapi/templates/response-schema31.ts
@@ -1,60 +1,113 @@
 import { compareFiles } from '../../utils'
 import { JsonPath } from '@netcracker/qubership-apihub-json-crawl'
-import { breaking, DiffAction, nonBreaking } from '../../../../src'
+import { annotation, breaking, DiffAction, nonBreaking, risky } from '../../../../src'
 import { diffsMatcher } from '../../../helper/matchers'
 
+const COMPONENTS_SCHEMAS = ['components', 'schemas']
+
 export function runCommonResponseSchema31Tests(suiteId: string, commonPath: JsonPath): void {
-  test('Add union type', async () => {
-    const testId = 'add-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.add,
-        afterDeclarationPaths: [[...commonPath, 'type', 1]],
-        type: breaking,
-      }),
-    ]))
-  })
+  describe('Union type', () => {
+    test('Add union type', async () => {
+      const testId = 'add-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.add,
+          afterDeclarationPaths: [[...commonPath, 'type', 1]],
+          type: breaking,
+        }),
+      ]))
+    })
 
-  test('Add null to union type', async () => {
-    const testId = 'add-null-to-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.add,
-        afterDeclarationPaths: [[...commonPath, 'type', 2]],
-        type: breaking,
-      }),
-    ]))
-  })
+    test('Add null to union type', async () => {
+      const testId = 'add-null-to-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.add,
+          afterDeclarationPaths: [[...commonPath, 'type', 2]],
+          type: breaking,
+        }),
+      ]))
+    })
 
-  test('Remove union type', async () => {
-    const testId = 'remove-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.remove,
-        beforeDeclarationPaths: [[...commonPath, 'type', 1]],
-        type: nonBreaking,
-      }),
-    ]))
-  })
+    test('Remove union type', async () => {
+      const testId = 'remove-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.remove,
+          beforeDeclarationPaths: [[...commonPath, 'type', 1]],
+          type: nonBreaking,
+        }),
+      ]))
+    })
 
-  test('Remove null from union type', async () => {
-    const testId = 'remove-null-from-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.remove,
-        beforeDeclarationPaths: [[...commonPath, 'type', 2]],
-        type: nonBreaking,
-      }),
-    ]))
+    test('Remove null from union type', async () => {
+      const testId = 'remove-null-from-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.remove,
+          beforeDeclarationPaths: [[...commonPath, 'type', 2]],
+          type: nonBreaking,
+        }),
+      ]))
+    })
+
+    test('Reorder types in union type', async () => {
+      const testId = 'reorder-types-in-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toBeEmpty()
+    })
   })
 
-  test('Reorder types in union type', async () => {
-    const testId = 'reorder-types-in-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toBeEmpty()
+  describe('$ref sibling properties', () => {
+    test('Add sibling description for ref', async () => {
+      const testId = 'add-sibling-description-for-ref'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.replace,
+          afterDeclarationPaths: [[...commonPath, 'description']],
+          beforeDeclarationPaths: [[...COMPONENTS_SCHEMAS, 'Pet', 'description']],
+          type: annotation,
+        }),
+      ]))
+    })
+
+    test('Change sibling enum for ref', async () => {
+      const testId = 'change-sibling-enum-for-ref'
+      const diffs = await compareFiles(suiteId, testId)
+      expect(diffs).toBeEmpty()
+    })
+
+    test('Change referenced enum when sibling exists for ref', async () => {
+      const testId = 'change-referenced-enum-when-sibling-exists-for-ref'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.add,
+          afterDeclarationPaths: [
+            [...COMPONENTS_SCHEMAS, 'Color', 'enum', 1],
+            [...commonPath, 'enum', 1],
+          ],
+          type: risky,
+        }),
+      ]))
+    })
+
+    test('Remove sibling maxLength for ref', async () => {
+      const testId = 'remove-sibling-maxLength-for-ref'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.replace,
+          beforeDeclarationPaths: [[...commonPath, 'maxLength']],
+          afterDeclarationPaths: [[...COMPONENTS_SCHEMAS, 'Color', 'maxLength']],
+          type: breaking,
+        }),
+      ]))
+    })
   })
 }
diff --git a/test/compatibility-suites/openapi/templates/schema.ts b/test/compatibility-suites/openapi/templates/schema.ts
index 8c25371..4c07979 100644
--- a/test/compatibility-suites/openapi/templates/schema.ts
+++ b/test/compatibility-suites/openapi/templates/schema.ts
@@ -1101,8 +1101,8 @@ export function runCommonSchemaTests(suiteId: string, commonPath: JsonPath): voi
     test('Update definition of free-form object', async () => {
 
       const testId = 'update-definition-of-free-form-object'
-      const result = await compareFiles(suiteId, testId)
-      expect(result.length).toEqual(0)
+      const diffs = await compareFiles(suiteId, testId)
+      expect(diffs).toBeEmpty()
     })
 
     test('Add non-boolean additionalProperties', async () => {
diff --git a/test/compatibility-suites/openapi/templates/schema31.ts b/test/compatibility-suites/openapi/templates/schema31.ts
index f7434e3..0202603 100644
--- a/test/compatibility-suites/openapi/templates/schema31.ts
+++ b/test/compatibility-suites/openapi/templates/schema31.ts
@@ -1,60 +1,113 @@
 import { compareFiles } from '../../utils'
 import { JsonPath } from '@netcracker/qubership-apihub-json-crawl'
-import { breaking, DiffAction, nonBreaking } from '../../../../src'
+import { annotation, breaking, DiffAction, nonBreaking } from '../../../../src'
 import { diffsMatcher } from '../../../helper/matchers'
 
+const COMPONENTS_SCHEMAS = ['components', 'schemas']
+
 export function runCommonSchema31Tests(suiteId: string, commonPath: JsonPath): void {
-  test('Add union type', async () => {
-    const testId = 'add-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.add,
-        afterDeclarationPaths: [[...commonPath, 'type', 1]],
-        type: nonBreaking,
-      }),
-    ]))
-  })
+  describe('Union type', () => {
+    test('Add union type', async () => {
+      const testId = 'add-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.add,
+          afterDeclarationPaths: [[...commonPath, 'type', 1]],
+          type: nonBreaking,
+        }),
+      ]))
+    })
 
-  test('Add null to union type', async () => {
-    const testId = 'add-null-to-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.add,
-        afterDeclarationPaths: [[...commonPath, 'type', 2]],
-        type: nonBreaking,
-      }),
-    ]))
-  })
+    test('Add null to union type', async () => {
+      const testId = 'add-null-to-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.add,
+          afterDeclarationPaths: [[...commonPath, 'type', 2]],
+          type: nonBreaking,
+        }),
+      ]))
+    })
 
-  test('Remove union type', async () => {
-    const testId = 'remove-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.remove,
-        beforeDeclarationPaths: [[...commonPath, 'type', 1]],
-        type: breaking,
-      }),
-    ]))
-  })
+    test('Remove union type', async () => {
+      const testId = 'remove-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.remove,
+          beforeDeclarationPaths: [[...commonPath, 'type', 1]],
+          type: breaking,
+        }),
+      ]))
+    })
 
-  test('Remove null from union type', async () => {
-    const testId = 'remove-null-from-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toEqual(diffsMatcher([
-      expect.objectContaining({
-        action: DiffAction.remove,
-        beforeDeclarationPaths: [[...commonPath, 'type', 2]],
-        type: breaking,
-      }),
-    ]))
+    test('Remove null from union type', async () => {
+      const testId = 'remove-null-from-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.remove,
+          beforeDeclarationPaths: [[...commonPath, 'type', 2]],
+          type: breaking,
+        }),
+      ]))
+    })
+
+    test('Reorder types in union type', async () => {
+      const testId = 'reorder-types-in-union-type'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toBeEmpty()
+    })
   })
 
-  test('Reorder types in union type', async () => {
-    const testId = 'reorder-types-in-union-type'
-    const result = await compareFiles(suiteId, testId)
-    expect(result).toBeEmpty()
+  describe('$ref sibling properties', () => {
+    test('Add sibling description for ref', async () => {
+      const testId = 'add-sibling-description-for-ref'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.replace,
+          afterDeclarationPaths: [[...commonPath, 'description']],
+          beforeDeclarationPaths: [[...COMPONENTS_SCHEMAS, 'Pet', 'description']],
+          type: annotation,
+        }),
+      ]))
+    })
+
+    test('Change sibling enum for ref', async () => {
+      const testId = 'change-sibling-enum-for-ref'
+      const diffs = await compareFiles(suiteId, testId)
+      expect(diffs).toBeEmpty()
+    })
+
+    test('Change referenced enum when sibling exists for ref', async () => {
+      const testId = 'change-referenced-enum-when-sibling-exists-for-ref'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.add,
+          afterDeclarationPaths: [
+            [...COMPONENTS_SCHEMAS, 'Color', 'enum', 1],
+            [...commonPath, 'enum', 1],
+          ],
+          type: nonBreaking,
+        }),
+      ]))
+    })
+
+    test('Remove sibling maxLength for ref', async () => {
+      const testId = 'remove-sibling-maxLength-for-ref'
+      const result = await compareFiles(suiteId, testId)
+      expect(result).toEqual(diffsMatcher([
+        expect.objectContaining({
+          action: DiffAction.replace,
+          beforeDeclarationPaths: [[...commonPath, 'maxLength']],
+          afterDeclarationPaths: [[...COMPONENTS_SCHEMAS, 'Color', 'maxLength']],
+          type: nonBreaking,
+        }),
+      ]))
+    })
   })
 }