Talking about what someone would have wanted only makes sense if that person is dead.
If the person you’re talking about is still alive, talk about what they do want.
And assume that they want to live. Almost everyone does.
Even if they’re brain damaged, even if they’re in pain, even if they have dementia, even if they no longer recognize people.
They’re still a person. They’re still there. And they still want things.
So don’t ask what they would have wanted. Ask what they do want.