Hello, lilsister, and welcome to the forum. This is actually a moral dillema, for which I'm sure there are many differing opinions. Has your brother actually sent in all the paperwork and medical records for his disability application? He needs to get up-to-date lab work, scans, etc., to include with the application. Is he currently getting any medical care? I can tell you that he cannot be considered for a transplant without 6 months of documented sobriety in AA (usually.)
If mom and dad are providing room and board, paying for his meds and car insurance, why on earth would he need $400 a month to "live on?" I think SOMEONE should say something to the parents about that being an absurd amount of money. He has it made in the shade, not having to worry about bills and getting all that spending money, too. Your parents are enabling him and someone should set them straight. Sorry if this seems harsh, but I call it as I see it.
Hugs,
Connie