It seems like something she should have discussed in detail with you first. Like had a session where you talked about it. My T has occasionally floated the idea of me bringing in one or both of my parents for a session, but he said if I ever wanted to do that, we'd want to do a bunch of discussion beforehand to figure out what I want from it. Now, it would be different for me because this would be addressing stuff from my past, most likely. While this would be about your parents supporting you now.

But I could definitely see being uncomfortable about it without discussing it with your T beforehand--like does she know what your parents do and do not know about your mental health? Is there anything you'd prefer she keep private? I'd consider asking if you can just do a regular session, then set up a time to meet with your parents in the future.