My mom has blown off my kids and I for years. Like you, it used to really bother me. A long time ago my friend shared that her mother did the same and she (my friend) made it a point for each time her family blew off her kids-she would make sure to spend an hour doing something she wished her family would do with her kids.
It's meant my house was a lot less clean, but my kids got to experience other parks, other libraries-not close to us. They have had basic sewing classes, scrapbooked, learned to knit, etc. All things my grandmother did with me, that my mother missed out on doing with my kids, I did with my kids. It has enhanced my relationship with them growing up.
Learn from my wise friend- give piper more of your time and she won't miss out on grandma.
Hugs, if I loved closer- I would be an adopted Grammy. Grand kids are the best!