I have been a caregiver to both of my parents and live in their home. My brother is the power of attorney and my father (mother now deceased) is in rehab. My brother has told me my father will not be allowed to go back home and I have to get out because he is selling the house. My father objects. Can he do that? Brother does not live there.
So the important first question is, has Dad been declared by a court to be incompetent? If not, would he likely to be if it went to court -- are there doctors who would say that he can no longer act in his own best interests? Start there.
When brother says Dad "will not be allowed to go back home" -- is he quoting a doctor or some medical professional, or is he making that decision on his own? Does he have both Financial and Medical POA? And, most important of all, has Dad been declared legally incompetent?
If Dad is still competent to make decisions, he can decide to name you POA, for example.