Privacy and missing things when skid here
Longtime lurker, firsttime poster, so I'm familiar with a lot of the regular names here. DH and I have been married for 6 years and have a 3 yr old and 6 month old. SS11 lives in the next province over after his mother took a job promotion 3 years ago. We see him on school holidays, 6 weeks in summer and other long weekends throughout the year. The problem is, the last couple of years there has been stuff missing that I've noticed after he's left. Nothing worth a lot, but with sentimental value: a souvenir glass, a couple of pictures of my bio kids that I've had in my desk in envelopes, a scarf given to my toddler by her grandmother, my toddler's favorite teddy that she used to sleep with, that sort of thing. Additionally, I've heard him say mean things a couple of times to my toddler when he thought I couldn't hear him (I was in the next room momentarily).
And on top of all that, this last time he came to visit during Christmas break, he had a tracking device on his shoes called the Jiobit! DH was angered by it and removed it until he went back to his mother's.
We are gearing up for yet another spring break visitation and I don't know what, if anything, I can do to prevent the missing of items. I thought it might be my toddler, but I would think that things would turn up in the house if that were the case. But I turn the house upside down looking for these items. We also live as much of a minimalist lifestyle as we can with two young kids, so I don't think these items are misplaced. Any experience with this sort of thing? Advice?
Just so you know, BM isn't remarried, has been quite needy and inappropriate with my DH even after we had our toddler, but hasn't been particularly high conflict.
AND, DH wants SS11 to be able to stay in the house on his own in the future, which I am uncomfortable with, given the missing items.