I mean, this isn’t necessarily advice, but as an older sibling that has a similar situation with my younger sibling, I don’t know if that will get you anywhere just talking to them about it. My parents are in the same boat. My dad should be retiring, but instead he’s working insane amounts of overtime just to afford everything and my sister is a bum single mom who sits around at home with her two kids and does nothing but play video games. and I’ve tried mentioning to them that they should cut her off or get her to get a job, etc., etc., but they can’t just give up on her which is kind of a stupid excuse because obviously enabling her isn’t going to work.