My hubby wrote her a letter...making it very clear the Grandparent's role and the boundaries. She got it on Sunday. Hubby talked to his dad today and they have agreed to live by those boundaries.
Here is the letter...names have been changed
Mom,

Since I have a hard time talking to you without getting upset on sensitive issues, I have decided to write you. I have multiple reasons why I am declining to let Beth participate in the upcoming pageant with you. You are always so careful that you don't spend a dime more on one child than the other, but when it comes to time spent, phone calls, lunches and other things the balance is far from fair. The phone will ring 3 times a week from you for Bray, but never for Beth or Ellen. Pageants are something that parents should take care of. I don't want to give the impression to anyone that Grandma had to step in and do what Me, Stephanie and Renee (hubby's ex) should be doing and we would have been doing if the child had shown one ounce of interest until now. If you want to help by sponsoring Beth, or help get her a dress like Stephanie's mother did with Ellen that is fine. Any help beyond that is not needed. Where Renee may not choose to participate, Stephanie is more than happy to. In all honesty, Stephanie does not need help getting either girl ready for a pageant, as she has done it for 3 years by herself with no help from any Grand Parent.

If you want a relationship with Beth, pick up the phone and call her, go have lunch with her, go to one of her volleyball games, have her over for dinner, or take her to the mountains. Any of these things fall under the category of "Grandma", but pageants, proms, weddings and such fall under Mom and Dad. When and if you decide to start doing these things, remember that there is a 3rd grandchild here as well that enjoys her time with the 2 of you. Don't think for a second that both Beth and Ellen haven't made numerous remarks over the years about how "not special" the 2 of you make them feel. I have said these things for years, but it just falls on deaf ears.

We have discussed several times the respect that I expect when it comes to MY children. It is a constant argument, and I am sick and tired of being sick and tired. I just want to live in harmony and when it comes to the people in this family they make it impossible. I truly appreciate the stress you put on me on my birthday. You couldn't just call and say happy birthday. No, you had to use my birthday as a way to pressure me about the pageants. I stressed all day long over it. That was such a nice way to spend my day.

The choice is yours on pursuing relationships with your grandchildren. I gave several suggestions and would be happy to listen to any that you may come up with, but pageants are not an option. That is our responsibility and we gladly accept it. This is not open for discussion and I would prefer this to be the last time I have to say no.

I love you both,
Chad