My dad was diagnosed with mixed dementia in 2015. Things weren't too bad for a few years, until I got power of attorney for his finances. He very quickly became paranoid I was stealing his money. I just kept reassuring him I would never do this. For Father's day I bought him a new watch that speaks the time and date (he can never remember the date). He really liked his new watch,but now it's causing problems. He's now accusing me of stealing his old watch. He says I ripped it off his wrist and said I was going to throw it away. He's obviously dreamt about this and believes it is real. It doesn't help that he's put the watch somewhere and can't find it. How do I deal with this? Has this happened to anyone else?