Sorry another MIL thread

I think your DH needs to grow a backbone and say something like:

"Actually Mum, its not ok to just cancel - especially when its because you're tired from looking after X kids and my kids were excited to see you. How about you prioritise your GC equally and stop being so unfair with your time. You see X children all the time and never see my kids. Its rude at best and cruel at worse. My daughters are asking questions why you don't seem to bother and its hurtful for me to awnser those questions. Ultimately it is up to you to have a relationship with them/me - but dont be surprised if we match your energy and dont prioritise you in our lives anymore. We will see if if you make effort and it suits us/when we're not tired. If not - your loss. Enjoy the week"

Then match her energy from there on.

I suspect your MIL is actually spending time with her adult daughter rather than her grandchildren by her daughter (as in, it’s adult time with young children who have to be there). She probably doesn’t have the same sort of relationship with her son, and definitely not you. She’s just not interested in children, probably.

Do you send her photos or update on social media regularly? Some people think they are 'in touch' because they see what you are doing, latest photographs even though there has been no physical (or by phone) contact for an age.

Knowing that your girls see the other grandmothers, I bet she justifies her distance by saying 'They are all for her family, I don't get a look in'. Generally on here, DHs do not like to make a scene and want to keep the peace but has he told his mother how hurt and disappointed he is with her lack of interest.

It must be rotten for him to think his mum cares more about sisters kids than his.
Because it must hurt.

If she let's them down I'd stop telling the kids about potential plans. I'd wait until the last minute to tell them.

Op your not wrong. Its frustrating drives me nuts. Mil does similar, will actually do stuff with SILs kids where with mine they end up hanging around the house watching tv all day.
I can see my oldest especially loosing all interest in GPs.

You are not wrong to feel that way. But match her energy. Seek the connections elsewhere. It doesnt have to be a biological grandpare t relationship that gives your children that connection.

You cant make mil care so dont spend your energy on her..

For me it was my mother who wasnt interested so I build a close relationship with mil. Result is the children speak lovingly about mil who passed 5 tears ago. Rarely mention my mother as they have no memories of her. They just accept that is how it was. It was the norm for them.

Your not wrong to feel this way . But there isn't really anything you can do about it. You can't force her to take an interest. It's a shame for your girls and I can understand why you feel defensive on their behalf . You don't know the dynamics of SIL relationship with her mother . MIL might feel pressured to provide childcare .