I have written before and am on the verge of burnout. The opportunity has opened up to move my husband's elderly parents to his sister's farm close to town. We live 7 miles away from town on a mountain. His mom is all for it but his dad, who has dementia, refuses to move and stop driving. He has had close calls driving and is 90. This move would be really good for them - how can we get him to go?
She knows what you are dealing with, and she can do better? (He would probably be much better off if he were to go to Memory Care as long as you are moving him to another residence.)
Get your FIL to sisters house. (your are going to visit, you are going to stay the weekend while we get work done on the house....)
Get his favorite chair and any familiar furniture there and set up before he arrives so he feels at home.
Tell him his car can stay at "home" and you will bring it next week when he is settled in.
Next week tell him..
The car won't start
The car needs gas
The car is in the shop
Keep making excuses as to why the car is not being brought to him.
You can not "reason" with a person that has dementia. Most likely he will settle in having his wife with him as the person he is more familiar with.
He can either come along to be with his wife, or he can stay by himself.
If you put it to him that way, do you think he's see that he needs to move? Of course if you leave him, you call Adult Protective Services and report him as a vulnerable adult. In that situation, the State will probably take guardianship.
The thing is, as we age, we can either make choices before we are incompetent to make them, or we risk having strangers make them for us.
Stubborn people rarely get good end of life care.