can a lawyer legally represent a family member in ny sate

my sister is a attorney in Niagara county ny. my mother became ill in 2005 with b12 deviancy. this causes dementia hallucinations. She owned her home bought though a personal injury lawsuit. the funds were always kept in her sole bank account and her home was bought in he name only with those funds. she was incompetent to do anything legally. With I in week my father a sister quick deeded her house and a power of attorney to my father. we believe they even forged the papers. They stole over 280k in long term disability and social security checks. my sister is also helping my father hide a family coin collection in excess of 2 million. my father also has given my sister over 60k to set up a private practice and settle a malpractice suit from the last law firm she worked for.. My father by the ay only brings in 1200.00 a month. There is no doubt she and my father stole her assets, We also have good reason to believe she drew up the divorce documents and 81 using a friend probono.