Perhaps just asking the therapist what types of questions she considers appropriate versus inappropriate could be a place to start. You could then even say the subject area you were interested in to get a feel before diving into specific questions.
I have refused to answer questions about my income for example - as being unnecessary to why I go see her and since I pay in cash weekly, no valid concern over whether she would get paid, I never balked at the fee she charges and so when she asked what I got for doing a certain type of work I do, I responded by asking why that was therapeutic for me? She said she was just curious - which did not convince me it was reasonable for me to answer. I am not there to satisfy her prurient interest.