There are way too many variables in the situation to give you a pat answer; however, you should attempt to slowly enhance, or improve the relationship, so that the main thing, what is better for the children, can wind up being the main concern for you and your grown children.
I have dealt with a situation similar to what you are going through, and everyone told me to not rock the boat, by having a chance of losing any contact with my granddaughter. I chose to confront, and take that risk, otherwise, I felt, I would have to be at the mercy of my daughter, the rest of my granddaughter's childhood, and by then without a relationship with my granddaughter, she would probably not have the interest in having contact with me.
It kind of worked out for me. I have more time with my granddaughter, but my daughter in the beginning, did threaten me with not seeing my granddaughter. She eventually need my help and came to me with conditions I did not feel was within my ability to live with, so I refused, and she finally came around. I feel I was lucky, and it could have totally gone the other way.
You just have to use your judgment, know how they may act, and if things get worse, give them time to cool down, and rethink things, and they may, as my daughter did, come around. If not, some states have grandparents laws, at least I think they still exist, and then you could consider that.
One of my concerns is why both of your children are having the same reaction? Maybe you need to do some introspection, and see if there are things you may need to change as far as your behavior, as these children are THEIRS to raise, and you can suggest, but Mom and Dad, have the last word, and accept it. You may not agree with their parenting skills, but unless any real harm is coming to the children, you may want to stay clear of that subject.
My daughter is not raising my granddaughter the way I would like, but my granddaughter is well adjusted, so something is going right.
I hope this helps. Good luck, and please keep us posted, as I am sure there are plenty out here with situations close, and would love to know how you handle it, as well as the outcome.
