My father passed on Sept 27 leaving my mom the sole beneficiary. My mom obtained her own POA for health, finances and a will. My mom appointed me and my younger brother as her POA. We did the legal changes to the bank accounts. Question is my sister is opening my mom's mail, had the address changed to her address and deposited/forged my mother’s signature on pension checks she’s receiving. She’s deposited them into my mom's account but is this legal for her to change the address to her address, open her mail and make deposits when she’s not the POA for my mom? And she’s making accusations and filed a claim for elder abuse in which we have a text message saying the elder abuse people are watching us really closely.