By default, anyone in a group can invite their BBM contacts to join the group, so you can meet new people without having to necessarily add them as BBM contacts. If a group already has 30 members, you won't be able to join until someone leaves the group. You can also start your own group.
Whoever creates the group can automatically control group membership, update the group's profile picture or name, and disband the group and delete all of the shared data. Additional admins can be added after that.
When you create a group, you automatically become an administrator for the group.
The group and all of its data is removed from your BlackBerry device when you leave a group.Other members continue to see the items that you shared, including pictures and lists.
If you're an administrator for the group, you can choose to delete the group and all of its data when you leave.