Arron,
My Dad gets up almost every night to go to the bathroom and usually he goes right back to bed,,but sometimes he goes out to the kitchen,,,,thinking it's morning,,,,or he'll go into another bedroom and he has a few times left the house. Luckily my mother has become attuned to his movements and she thinks that alot of the time he's still sleeping or semi-asleep. He doesn't remember anything the next day.
I think the story of someone telling your father in law to go to the cemetary is a halluncination. My Dad doesn't mention them much anymore,,,,,but almost everyday he would see these people behind the couch or they'd be in the bathroom and he would tell us they wouldn't get out. We found out that halluncinations can be a side effect of some drugs so I would check with your doctor. My father's doctor prescribed seroquel for the halucination but it made him sleepy during the day and up & restless during the night.
Hope I've been some help. Good luck with your father in law.
Lorry