Grandparents' claims don't match reality
Your mother is already providing regular childcare with one of her grandchildren. If you would like for her to increase her efforts, perhaps you could ask her outright if she could double up on those days and watch your kids, too. Or maybe they would be willing to host your children for an occasional overnight. Have you asked?
I'm suggesting that if you aren't getting what you want, then you should ask for it, nicely. Have you done this, or are you expecting them to intuit that this is what you want from them?
The way to correct their exaggeration of the role in your kids' lives is to have a private conversation, and tell them that you love them, but this bothers you.
You could try harder to fold these grandparents into your family by inviting them to spend time with you, to attend school events and to basically be with you when you don't really want anything from them.
Not to put too fine a point on it, but you and your children ARE probably lucky to have grandparents close at hand, even if their effort is disappointing. It would be unfortunate if you only realized this in retrospect, after they were gone.
Dear Amy: I am 65, and I met a wonderful woman. We were planning on getting married on the beach in Hawaii at my brother's time share, and then celebrate with family later.
I have four kids who say they want to be there when we say our vows. They cannot afford to go.
I told them that this is not our first marriage (we are both widowed) and we just want a small thing in Hawaii, and then to celebrate with them afterward.
My one daughter is getting married next month, and she said, "How would I like it if we went off and got married and then came back to celebrate?"
I feel that this is her first wedding, and it is a big celebration. We don't want a big wedding. We just want a small celebration. Should we say our vows in Hawaii, or should we save it for home?