I am the only DID in my group as well, even though another does have a dissociative disorder. The therapist was concerned at first about having me in there, and i felt really odd at first since it felt that she might be scared of me. There's nothing to fear. So, there's more people in me than in others, but they are still all people (some younger). One in us is an alcoholic and avoids AA meetings like the plague. For me in the one AA we went to, we stayed silent about who we are. For the group we are in now, we are slowly opening up over time. Not come out directly and said "I'm DID" since that tends to cause problems. But if T is switching, I'd ask her how she wants to move forward, and i'd put out info on DID to the women of the group, and let them know that there is nothing scary about it. All 9 of T are people and wish to be treated with respect. I'd be really uncomfortable if i sensed that many people had a reaction to me.
Good that you are seeking answers =)