I had medical and financial POA for my parents, which they established years ago. About 1-1/2 years ago, my sister took it upon herself to make her the POA for medical naming my brother second and her husband 3rd. My mother has Alzheimer's and would not have been able to make this decision wisely. She also had a friend witness the signing and another friend notarize. I do not think my father's signature on the document is his. How can I get this changed back to me?