Wow, pretty impressive - DFC and all the rest. I too hope he's well cared for. I can relate a bit to the obstinacy, my father too is in the early grips of dementia and Alzheimer's. I'm afraid what it'll be like if and when it gets worse.
It's incredible how quiet some older gents can be about their service - and that's impressive service from your father in law IMO. Last time I was in the hospital the older gentleman in the room next to me was a Mosquito pilot in the RCAF, Bill Williamson, and flew for Sikorsky for years after that as a test pilot in some of the early helicopters. I would bust his balls about being named "William Williamson" to make him laugh, and in trade he'd tell me stories about flying back then, it was fantastic, I wish I'd recorded them all. Very dignified in his final days, he was fortunate to not have a hint of any mental degenerative diseases.