I can't find the place where it says the Mother gave the abusive daughter power of attorney. I think someone neutral, who does not know the family or anyone connected with it, should talk to Mom alone, see if things are as they appear. Sis has had health problems and has a history of not keeping jobs very long. Thank god there's no alcohol history involved. Mom has provided her with a home and financial support for years.
Visits quickly degenerate into shouting matches with our older sister.
Verbal abuse might become physical 2. Mom might get stressed out and get prematurely sick and frail 3. Mom might actually go batty from the crazy stuff our disturbed sister is doing. I think your sister might need some counselling. Your mother may have given her power of attorney because she thought that may stop her daughter from verbally abusing her.