Did your T discuss this with you - then you could voice your reservations (if you have any) and/or doubts. It can help sometimes to bring in family members etc. but only when the client is ready and/or willing. Basically, it ought to be your decision and what is more comfortable for you. Otherwise, I don't see that it can be all that helpful.

If you are not sure yet, I think it is important to discuss this with T as it may suggest you are not ready yet. But maybe further down the line you might consider 'inviting' them...