I suggest you do an inventory of all his clothes, possessions, etc, when you take him in.
I name label all of DD’s clothes; she is supposed to do her own laundry with help; but still she comes home in other residents’ clothes. I go through her wardrobe and chest of drawers every time I go, to take out other women’s clothes. DD’s winter coat went missing for 3 months - it’s easier to ask where it’s gone, if you can point to the inventory with the make, size and description!
We let DD take in a photo album of members of the family, pets, our house, etc.
For DD, I had to fill in a 50 page form of every aspect of her day, from when she gets up until bedtime, so they could do a care plan. For example, breakfast, bathing, getting dressed, toileting, snacks, activities, lunch, dinner, getting ready for bed and bedtime. I had to describe how much help she needs at mealtimes - generally she can feed herself; but may struggle to work out how to get meat off a chicken leg with cutlery. Baths - she likes them lukewarm (due to sensory processing problems), but has no conception how to mix the taps to get that temperature of water. She can wash herself, but not her hair. Likes and dislikes of food for breakfast, lunch, dinner, drinks and snacks. How to communicate with her. Dos and don’ts of behaviour towards her. How she takes meds.
I saw the importance of this, when MIL was in a care home for a month - we never saw even a basic care plan. She was offered cups of tea, and egg sandwiches, when if there were one thing, the whole extended family knew about her; it was that she couldn’t abide tea, eggs and pork!
We don’t have this problem; but SIL did over MIL - MIL’s packs of incontinence pants regularly “disappeared” from her wardrobe, particularly when they moved her to another room! In the end, SIL told them, no more packs of incontinence pants were to go missing! Keep track of what you take in, if applicable!