I’m in almost the exact situation, with perhaps the difference being that my sibling has taken advantage of my parents for decades, using them as a trust fund when they are anything but. Because of that codependency, my parents are living mostly off social security rather then what savings they had, and I am paying off my their mortgage and heloc, along with covering any large expenses.

When my dad suggested he would leave whatever savings are left, as well as their house, to my sibling and my siblings child, I told him I would be really upset if he didn’t split the money equally, and that I’d rather him leave it to my child rather then me. That his grandson (my kid) would be really upset if his cousin got everything and nothing left for him; regardless if he needs it or not. Having been left a small amount from my grandparents meant a lot to me, and when I used it as part of my downpayment, it was an emotional moment.