As always, Equality has great wisdom. An explanation from the elder about why the split is "unfair" might help it in case of future lawsuit.
BC has a good point about paying the caregivers in the present, if possible. I know it's not always possible. Once my mother stopped being able to take care of her own affairs, I visited an attorney to help sort her affairs out. (For heaven's sake, an estate plan is not "I hope I'll die in my sleep at home," but that's what she had, apparently.) The attorney told me about personal services contracts to compensate family caregivers, and I wondered why everybody didn't know about this. It sounds like the reason may be that it's a state-level law that allows them, and it sounds like my state is trying to do away with them. At any rate, I was glad that my sister, who has had to do most of the hands-on care while I have handled ridiculously muddled financial end of things, was going to get some supplementation after having her life and home turned upside-down. Not that my life hasn't been significantly impacted, but not to the same extent as my sister. It's only fair. If people could reach an arrangement like that while the elder was still alive, there wouldn't be as much quarreling over the remains in the will.