Is there an alternative to withdrawing from relationship with mother when siblings can’t behave?

It is sad. You have to withdraw to have piece, yet withdrawal makes you feel cut off which you are. While it is sad I think the better choice is to do this, and allow for more peace, and less bickering. I hope you are settled in your own mind that you did all you could to get along, and that further messing in this would just cause further mess. I would say find a way to be at peace with that. There is an estrangement in my own family that is occasionally on a personal level very painful when I think about it; but when I DO really really think about all of it, I still find there to be no answer to it. Sometimes people just don't get along with one another. They are best out of one another's lives. I have had to ask myself a few times "if one of you dies suddenly, how OK are you with where this all is" and have had to answer myself that I am as OK as I can ever be with the situation, no matter what. I have an inner peace about it. There is NO ANGER, but basically an understanding to withdraw from one another, and to have just a few pleasant words a few times a year.
This sort of thing is never easy. But as a nurse I witnessed family trauma over they dying bodies of my family; it is something I have never completely got over. Death and illness is one thing, but that sort of thing is quite another. I would be at peace in so far as you are able, reassure yourself you did everything you could. Wish them well, and well away from you.
I think were I you the one question I would ask is "Is this an attempt to get Mom to take sides", because you are too grown up for that, and that won't happen in any meaningful way. If I loved my Mom I would send cards and letters and bouquets of love, and not really speak about the bro. Just would be "let's don't go there". But if there isn't not a lot of a relationship with the Mom OR the bro I would, as I said, wish them well, and well away.

TW, when you say you want to be compensated by your mom, do you mean you want to be paid for your time? Or are you asking for reimbursement for money that you lay out buying things that she needs?

There is a huge difference to my way of thinking and your mother may also not understand what you mean (I think you mean the latter).

I seem to recall that mom gave your brother POA. If that is so, then you should be submitting receipts to him for reimbursement from mom's funds.

I don't think I've understand the big pic here.. but is it possible to visit Mom in AL? Just visit her, be in that moment, not think or talk about the past or future (especially not brother if a sore point).

I don't know if that is even a wish? But if so, what is the barrier?

When I visit my sister we discuss favorites TV shows, her outings that week, favorites meals. I don't discuss any of the 'elephants' in the room as they are really just in my head: my thoughts that her living alone is precarious & that I feel her enablers should change direction etc.

Is that your barrier? Past & future thoughts big as elephants preventing the present?

I guess your talking about reinbursement for things you got her she needed or wanted. Tongue and cheek here, maybe you should have presented brother with a bill if he is handling the money. To be honest, as her POA he should be making sure her personal needs are met. Lets say its Depends, believe me he will get a call she needs them. Shampoo, toothpaste, etc. he is getting the call. Als do not provide these things as u know.

You can't do anything about inheriting. And this has been mentioned on the forum before, grandchildren inheriting from grandparents. IMO, grandchildren are not entitled to an inheritance. My girls are beneficiaries in our Wills if we are both gone. If they want to give any of that money to their kids, thats up to them. Or, you have a trickle down effect. If one of the children dies, their share of the estate is split among the grands. But I don't feel a grandchild should expect anything from a grandparents estate.