I feel for your situation but you do have choices. You could choose to have a normal relationship with your family and if wife and jw's don't like it let the chips fall. YOU as the man of the house can make decisions that would make it difficult for the jw's as well! pulling your financial support to the worldwide pedophile fund would be one of many things you could do.
I hate to say it but if my family did not accept me and my husband along with the kids as a family unit my kids would not see their grandparents, period. I would want to protect my kids from such a harmful situation. That is what the cult is, harmful, spiritually, emotionally and at times physically and/or sexually abusive. My job as a parent is to protect my kids from harmful situations.
You have a choice to put a corporation/org and the cong (as well as your own standing) before your own child or allow for natural affections and show unconditional love to your child on a daily basis not just passing in the street or quick non meaningful conversation as she passes the kids over to you while she shows you unconditional love by allowing you to see your grandchildren.
That is your legacy to your grandchildren, that is what they will remember when you are long gone. Grandma & grandpa didn't like mom for some reason or they will know it was because of the jw's and that will be the legacy of the jw's that gets passed on in that family. A damn good reason not join! no?
Sorry if this was harsh I didn't intend it to be. I find the whole shunning thing so damaging it really pisses me off.