Sunrise, it sounds extremely difficult and frustrating for you but I can sort of see your daughter's T's points. I had my life arranged and talked about behind my back as a child/teen (in the 1950's and 60's) and think I still resent it :-) I don't think you can "prepare" a person, even a child, for something or even soften the "blow" necessarily because it's another person and one can't know how that person is going to take whatever or react to it even if one knows the person well. Your daughter's thoughts, feelings, actions, etc. are autonomous just like ours are.

The therapist isn't there as a go-between between you/your husband and daughter; you have to talk to your daughter yourself and tell/try to help her with whatever family problem is coming up. The therapist can only work with her in the "present" which means after whatever happens, then they will discuss it (like after you were to talk to her and discuss wanting to talk to her T, then they would talk about that). One-on-one/individual therapy means exactly that, no matter what the age of the client. The therapist is there for your daughter, not to help your husband with behavioral issues he has with his daughter or to try and make you feel a bit more comfortable that your daughter will be "all right" when you have to give her difficult news to deal with in the future.

Think what you'd like for yourself in your individual therapy and that's what any "good" therapist is going to have with your daughter in hers. I can only imagine but it must feel very uncomfortable, complicated, and "foreign" compared to the normal parent/child way of relating!