Grandma says she will show up and often doesn’t

My Mom often says she is going to come over and she does not. I think I’ve finally accepted that this is just what Mom does – she says she will be over and she may or may not come – I don’t plan on her coming most often.

However, I’m not sure how to manage this when it comes to my daughter who is 8. My Mom will often be watching my niece and says she will bring her over to play with my daughter and then she doesn’t come. Sometimes we make plans that they will play together and my Mom will either be late or not show up.

This is very hard for my daughter because she wants to play with her cousin she often ends up sad, angry and crying. I think it is ok to have these disappointments, but where it is so often I am wondering how can I help my daughter with some thought work. I’m not sure how to help her see that it may or may not happen when she is so excited to see her cousin.

Is there a way to help her do a model or use another tool for this?

I couldn’t really see how a boundary would work. I’ve tried asking Mom to show up on time or why she is late and she gives me excuses or blames other people for her lateness.