Group messaging makes it easy to hold a conversation with multiple recipients all in one thread. Unfortunately, this feature is turned off on devices running Windows Phone 7.5 by default.
To enable group messaging:
- Open the Settings app.
- Scroll to the right, where the Applications section is located.
- Open the Messaging option.
- Toggle the Group Messaging switch to the on position.
Going forward, when you're included in a group conversation, or send a message to multiple recipients, the conversation should appear in the same thread. Keep in mind, group messaging uses MMS messages instead of SMS in order to keep everything organized, so make sure you're on an unlimited plan or use it sparingly if not.