I understand what your motives are and you are to be commended.
I have a relative that calls to check on me from time to time. He asked if I had gone back to the meetings, had I written to ask for reinstatement, etc, etc. My ex's son lives with my ex now, he is 15 and he used to be forced to attend the meetings when he lived with his mom in Alaska. Well, now that he never goes, I asked him how it was going, did he miss the meetings, etc. I asked WHY he didn't want to go. He told me that it was too much like school. Too much studying. So, I asked if he would go if he didn't prepare. He said no cuz he would be going alone. I said I would go with him. He said no thanks. My relative was shocked I'd offer to go.
My point JWbot, is that if we facillitate them, eventually, their true feelings may be able to surface. My "step-son" was given every opportunity to attend the meetings..........no studying, I'd drive him and I'd sit next to him. HE DECIDED he didn't want to go. Maybe your sister will get shunned and even go to a few meetings (I did) but eventually the shunning gets to you.