calamity,
Forgive me for not reading all of the posts. I understand your dilemna and I just wanted to tell you that in my opinion......the only way to protect your child and let her visit your mom, is to teach your daughter where the jw's are wrong and why. I have a daughter the same age who knows what the bible actually teaches and she is capable of handling my family. All maturity levels are different but I don't feel that my daughter is mature for her age compared to others. In fact, she is still very kid-like but she has an understanding of Jesus and that makes her immune to the jw's. My son is only six and I would never allow him to be alone with them because of his age and lack of ability to grasp truth from error just yet. My kids do not ask to visit my parents b/c I take them to visit occasionally and they know not to teach my kids. I don't think that my parents care either way if they ever see my kids or not, truthfully.
The only other thing that you can do imo is to tell your parents that you do not want them to speak about religion with your child and ask your little girl if they do.If they do... Then you have a solid reason to keep her from them and someday she will understand that. To your little girl, it may seem like you are the one who is shunning. If you disagree with those 2 suggestions that maybe you could try to stomach your mom for an houror two once a month while you visit her with your daughter. I'm out of ideas..lol My best to you and your daughter. love, dj