Ignoring the morality of it, from a purely economical and financial perspective the cost of elder care for a couple is very expensive, usually averaging around the price of a home, or most of the inheritance. It's basically liquidate the house now to send them to a nursing home, or ask a family member and "pay" them later with the house.

Hence the typical silent agreements that the sibling who looked after the parents before death gets the majority of the inheritance.

Silent, verbal, or even legal agreements are messy though. Talk to family members with the help of a lawyer.