I would want to know more of what T wanted to do. I don’t think it is fair to have a friend come as “support” and find themselves in a therapy session nor do .i think it fair to have a friend come to be set up to tell T negative things about you.
I have gone with friends as a support but set a VERY clear boundary with the T that it is NOT my session I am only support. When a fried/roommate of mine were both in counseling at the same counseling center (different T’s same supervisor) she told her T she wanted to kill me... so there was a meeting with her, her T, the supervisor and me (my T wasn’t available but I hated her anyway and I knew and liked the supervisor). It went well but in large part because I would not trash my friend. I don’t know what they would have done if I had reacted differently. I knew my friend was having transference issues with me and I suggested a safety plan. I never judged her, I don’t think that would be fair in THAT setting. I have had friends come with me twice with my first T but it didn’t help (or hurt), T and I were just not a good fit and nothing helped.
Current T is happy to have anyone I would like come with me to session. He is VERY experienced in groups and very strengths based. My husband and son may come with me at some point (seperatly) but I don’t really have any friends so couldn’t bring one. Closest I have is a former friend that was abusive that I still have minimal contact with. T would allow it and support me but wouldn’t really be comfortable about it especially when/if he knew about the abuse.