I was thinking your aunt was like mine (who will be 86 in April :-) and alone in parenting your sister. Turns out it sounds like she's my age, LOL.

I'm glad the meds are helping. I don't know if residential would help or not. My husband's nephew had residential when he was that age, a couple years ago and it helped. It's expensive though; my brother-in-law had to spend his whole inheritance from his father's death on the school.

I guess I'd try good humor, laughing gently at your sister's naive wanting $20 cash a day or plasma TV's, etc. I'd try to figure out a way to educate her about "how things work" in the real world.