About BBM Groups
You can use the BBM™ Groups feature of BlackBerry® Messenger to create or join a group of people that you want to stay connected with, such as family, friends, or co-workers. In a group, you can chat, share pictures and lists, create appointments, and more. Each group can have up to 30 members, and you can be in a group with people who aren't part of your BBM™ contact list.
Depending on your wireless service provider or organization, this feature might not be supported.