at least 2 of my siblings did this to my mom... her letting them walk on her was a strain to our relationship period.There was an interesting discussion I read once on "weaponized grandchildren".....grandchildren who are used as pawns by parents against the grandparents. For example, "If you don't lend us some money, you won't be seeing your grandchildren again", "If you don't agree to babysit five days a week, then forget about seeing them at all", etc.
I have seen that in action.
grandparents are important to be there for children.... i live 5 hours away but have drove over to babysit for important events because my SIL parents who live 5 minutes away are being used by his siblings by the use the child as a pawn method and now they have no time for our shared grandkids ......breaks my SIL's heart.