You could sure voice your wish, which might be helpful just to say aloud, but just be prepared that this sort of interaction outside the therapy room is not likely to happen. Also, as argo said, your therapist is going to be focused on her presenter role.

I have taken my mom to therapy. I warned my therapist that my mom is very likeable. The goal was to get my mom on board with a particular action to take to protect me against actions by other family members. I, of course, did all the work of bringing it up and making the request (several times), but my therapist--seeing that nothing was sticking--gently tried to take up my cause. It was not a complicated request, but my mom did not want to hurt another family member's feelings, instead choosing actions that placed me in the line of fire.

None of it did any good. The requests did not even register. My mom was very pleasant and (as I expected) somewhat charming, but it was like I said X and she heard Green. A couple months later, my therapist referred to that session and said my mother didn't have a maternal bone in her body. So, in that way, it was worth having taken a parent.

I share this as an example of having a therapist see other family members. She did not initiate anything on my behalf, but once I tried on my own and repeatedly failed, she tried to reinforce what I was saying. In the end, it was helpful to have my therapist see for herself what I was up against, and that I was not making things up.