Oh my gosh, I hate when my mom comes into my sessions! She doesn't anymore, but if something "big" happens, she does. And my T gives her the option! That drives me insane because my mom always makes things seem worse than they are, or brings up things I don't want to talk about. I would talk to your T and your mom (not together, unless you want to) and tell them you don't want her (your mom) in there during your sessions. They are individual sessions for a reason. It would be best to voice your opinions/feelings out into the open. Hope this helps, take care.