One important rule is YOU ask the questions and THEY provide answers.
They do NOT get to ask questions, and you do NOT answer any.
A simple question like: "is legalism apostasy" should see them tied in knots they can never unravel (provided you are fully familiar and can see and gently call their ignorance and misdirection, with more questions, or with a not satisfactory rating).
Personally I would forever hold out on them for a clear, honest, unambigious answer that makes sense and is from the heart and lines up perfectly with g79 6/8 pp. 27-28 (and ISoCF as well as CoC).