To create a group from a multi-person chat:
1. Tap the menu icon at the top of the chat screen.
2. Tap Other settings > Create group, or Create a group to use next to Albums/Notes.
3. Select the friends you want to add and tap Next.
4. Enter a name, set a profile photo, and then tap Create.
Note: Messages from the multi-person chat will not be transferred to the group. To view your past messages, you'll still need to check the multi-person chat.
For more information about groups, see here
Let us know if we can make it better.