re: Wife’s uncle is disrupting care plan for her father who has dementia

Anyone with half a brain nowadays knows about dementia and Alzheimer's.
The uncle cannot possibly be that clueless or else he is as hateful as he sounds, and he and his brother have inherited property and he want's it all.

Hospital and nursing home social workers might be able to help.

Years ago, a Jewish friend's mother had Alzheimers and her Father decided if he could just get her baptized, she would be cured. He kept taking her from the home where she was being cared for, and their son chased them all over D.C. to take her back to the nursing home. Sounds as if your Uncle could be about to do something similar. (Does your Father still have car insurance?)