If dad is incompetent by professsional's/state reports but not yet in writing, can he change POA?

My dad has alzheimers and it's worsening every day. He was just released from the hospital who reported him to the State since he did not go directly to skilled nursing as strongly advised. Dad is refusing the help he desperately now needs. I am POA and one of (3) healthcare POA which technically doesn't kick in until he's rendered incompetent. Dad's phys. put in writing he should make no medical decisions w/out POA (me) present. His lawyer knows this and has it also in writing. Can dad still do it and would the lawyer be willing as dad's attorney to do this based on anyone's experience?