How do you manage and navigate communications between estranged family members and the dying?

I brought my mother and grandmother home to live with me and my family this fall after finding them in dire straights. My mother has a terminal disease, and my grandma can barely walk, see or hear and poor memory. I am now full-time caretaking them both. My mother is at a point where she sleeps a lot and talks about dying. She wants to talk with her siblings. The thing is hardly anyone talks to each other anymore. Everyone is angry or doesn’t want to “deal anymore”.

I'm angry too. These ladies were dying and displaced because of wildfires and only one sibling called. The other who lives close by didn’t call and the other who lives across the country never called- their hometown made national news! I begged the one uncle who still talks to grandma to come help me with her, even for 48 hours (had free quality lodging, airfare and a car) and he told me to put her in a shelter if I couldn't handle it- during COVID?! (this is the son that calls her every day and says he loves her so much). When I told him I was upset that no one called or checked-in or made any effort to help, he said well people have a grudge because you were grandma’ favorite- remember the fight when you were 7?

7?! When I was a child, dropped off at grandma’s for weeks on end because my mother was a raging alcoholic?

I’m trying not to hold a grudge and accept they have their own histories with my mom and grandma, but how do I connect my mom with these people before she passes? How do I keep communications open for my mom and grandma as they near the end of their lives while protecting myself from their grudges and anger?

Family relationships are complicated. I suffered a lot because of my mother’s drinking but I see the value in taking care of them to help heal all this generational trauma. There is obviously so much more I could share, nonetheless I’ve tried to keep an open door for these family members in my heart but I no longer feel like tending it.