How do you deal with hallucinations: e.g. snakes going up the wall, curtains swaying, mice going under furniture, etc etc ect ?
We had Margaret Thatcher visiting, umpteen other uninvited guests, and Pam Ayres was a member of his Day Centre.
I would always deal with these people as if they were actually there.
For example, it would have been futile to tell John that (a) Margaret Thatcher wouldn't visit us and (b) she was dead, so I went into the hall, where John said she was waiting, and, talking to the wall, thanked her for coming, but said it wasn't convenient.
Then I opened the front door and, talking to the air, said "mind how you go!". John spent ages moaning afterwards, saying that her secretary should have made an appointment, so I agreed with him, as I agreed with most things.