Should I report my sister?

We have power of attorney over father affairs however, I live with him and take care of the bills, repairs and other expenses necessary as a caregiver. My sister said she works and so many words, do not have time to keep him sometimes and give me a break. My dad does go to an adult day center and I get a little break but my sister doesn't help me with the physical demands of caring for our dad. She does withdraw money out of his account to put in her savings account though. When I take out money, it is for our living expenses, credit card expenses, laundry and other living expenses. We haven't seen her in a month. I feel like since I am living with him 24/7 , i should be the one taking care of the money. She even said something about taking his money and him but says she works. Why should she have her hands in his money if she doesn't do anything for him but buy him a pair of pants once every 6 months? We have not seen this woman in a month and then when the 1st of the month comes, she withdraws $300 and deposits it in her savings account. Her excuse is to save for when we need money to help our father.