Hey, some people are like your siblings. My brother acted exactly like yours when both Mom and Dad were declining until they passed. He is only 15 months older than I am. I am a retired Physician but was working throughout all this and took it all upon myself. He did nothing except some financial matters for them. Mom and Dad would ask about my brother, I would say I dont know or I'd text him and have him call them which he did and of course they'd be so happy. It actually made me happy as well. He never saw either of them prior to them passing, he will live with this forever if he even cares. I have cut him out of my life. I have prayed about it many timers and I'm done. I am sure you have talked with your siblings about this but I pray actually that it will help. I know how hard it is.