Dad won't do physical therapy. Any advice?

This may be your brother’s way of accepting that Dad may not be around much longer. “Oh, he’s not really that sick. He’s just feeling sorry for himself!” Your brother will need to make his own peace with this. It sounds like it will be a reality soon enough. Don’t agree with him when he says Dad. Is having a “pity party”, but don’t argue with him either. Reinforce that Dad is very ill and leave it at that.