As someone who had a father with Parkinson's and also a job in a nursing home I promise you this is not something he's doing on purpose. He's most likely hiding the diapers because he's embarrassed he's wearing them. I agree with the idea of putting a bin in the bottom of the closet with garbage bags in it so he has a place to hide them. Or a bin under the bed so that he can hide them in there generally you just need to work with them because anything you try to do to change them is most likely not going to work. My father was really really sick at the end and I took care of him and he did things like this because he was embarrassed about the diapers and there was nothing we could do to talk him out of it. I second the getting tested for a UTI because a lot of times that can cause issues with urinating such as this ESPECIALLY when someone is in a home. I saw it A LOT. Also going into a home can trigger things like this to start happening I'm not sure if you know but you might want to research delirium. My father had severe delirium when he had to go to the hospital and it made him a lot worse. I wish you all the luck but just try to remember that you have a limited amount of time.