Shared subcriptions accuracy

Author: jlian

articles/iot-operations/connect-to-cloud/howto-configure-mqtt-endpoint.md

@@ -340,7 +340,7 @@ Then, follow the steps in [X.509 certificate](#x509-certificate) to configure th
 
 ### Event Grid shared subscription limitation
 
-Azure Event Grid MQTT broker doesn't support shared subscriptions, which means that you can't set the `instanceCount` to more than `1` in the dataflow profile if Event Grid is used as a source (where the dataflow subscribes to messages) for a dataflow. In this case, if you set `instanceCount` greater than `1`, the dataflow fails to start.
+Azure Event Grid MQTT broker [doesn't support shared subscriptions](../../event-grid/mqtt-support.md#mqttv5-current-limitations), which means that you can't set the `instanceCount` to more than `1` in the dataflow profile if Event Grid is used as a source (where the dataflow subscribes to messages) for a dataflow. In this case, if you set `instanceCount` greater than `1`, the dataflow fails to start.
 
 ## Custom MQTT brokers
 

articles/iot-operations/connect-to-cloud/howto-create-dataflow.md

@@ -376,10 +376,11 @@ sourceSettings:
 
 ---
 
-> [!NOTE]
-> If the instance count in the [dataflow profile](howto-configure-dataflow-profile.md) is greater than 1, shared subscription must be enabled for all MQTT topic filters by adding topic prefix `$shared/<GROUP_NAME>` to each topic filter.
 
-<!-- TODO: Details -->
+If the instance count in the [dataflow profile](howto-configure-dataflow-profile.md) is greater than 1, shared subscription is automatically enabled for all dataflows that use MQTT source. When this happens, the shared subscription group ID automatically generated. For example, if you have a dataflow profile with an instance count of 3, and your dataflow uses an MQTT endpoint as source configured with topics `topic1` and `topic2`, they are automatically converted to shared subscriptions as `$shared/<GENERATED_GROUP_ID>/topic1` and `$shared/<GENERATED_GROUP_ID>/topic2`. If you want to use a different shared subscription group ID, you can override it in the topic, like `$shared/mygroup/topic1`.
+
+> [!IMPORTANT]
+> Dataflows requireing shared subscription when instance count is greater than 1 is important when using Event Grid MQTT broker as a source since it [doesn't support shared subscriptions](../../event-grid/mqtt-support.md#mqttv5-current-limitations). To avoid missing messages, set the dataflow profile instance count to 1 when using Event Grid MQTT broker as the source. That is when the dataflow is the subscriber and receiving messages from the cloud.
 
 #### Kafka topics