AITA for pushing my grandparents to see my daughter more often

My fiancée (31F) and I (33M) have a daughter together (2F). My mom passed away in 2020, my dad lives on the other side of the country, and my fiancée's parents both passed away in 2014. That leaves the only grandparent figures to my daughter that live nearby as my own grandparents (69F and 72M), who live about 15 minutes away. My grandma (step, but has been a grandma to me my whole life) has an incurable cancer, and my grandpa has dementia that is early on but progressing. Partly for these reasons, we would like our daughter to get as many memories with them as possible while they're still around and before my grandpa's memory loss becomes severe.

There was one time we attempted an overnight stay with them while we were home by ourselves. It didn't go so well; she had a hard time going to sleep and was clear she has some separation anxiety. It wasn't all bad, but clearly something that needs to be worked on.

Ever since, my grandma, who between the two of them is usually the one we talk to and who makes decisions, has been quick to point out examples of her showing separation anxiety when around (which has become infrequent, the last time being on Christmas). When asking if they'd be willing to take her for a couple hours to get some time with her, whether just because or we have something to take care of, she refuses, saying she needs to get over separation anxiety before they can take her again. Our thoughts are that she won't get over it if we don't give her a chance to. And we don't exactly have a village of people able to help with that, as partly mentioned before.

Meanwhile, my grandparents frequently watch the kids of my cousin (25F), the kids being 6F, 4M, 3M, and 2F. She is no longer with either of the two fathers and has been known to frequently dump her kids on our grandparents. My grandma has said multiple times after various incidents of disrespect that she will not help my cousin anymore, but ultimately winds up doing so anyway. When we bring up these issues, my grandma claims that because these kids are not well taken care of (sadly true), she needs to keep a closer eye on them; we take this as our daughter being punished for being well taken care of. She also believes they do not have separation anxiety because of the rocky relationship with their mom, so they are more willing to be at their house. She takes our pushing that we accuse her of playing favoritism with the other kids.

We realize that someone has to watch those kids so their mom can work. My situation is more fortunate in that regard as I work while my fiancée is a stay at home mom. But we think there needs to somehow be more balance in the situation. And again, to have my daughter and grandparents to get plenty of time together before it's too late. So... AITA?