Don't Give Up
No matter how small the gesture, staying connected to grandkids and yes, also their parents is vital to maintaining the relationship. And when there is alienation, don't give up. Mail cards, gifts, letters to let them know that you're not going away and that you are thinking of them. And, if they restrict the mail, then prepare the correspondence as though you were going to send only keep it to someday give to the grandchild. Taking action is better than doing nothing at all.