It seems impossible to keep a high quality hearing aid with her when a family member isnt present despite having it attached to a cord on her shirt. The staff hasn't been able to locate all three expensive hearing aids lost by her in since 2019. My family, therefore, leaves her with a low cost over the counter one when we're not with her. (It doesn't work nearly as well, unfortunately). She is much more communicative and seems happier when she can hear well with the higher quality one that my family brings with us when we visit, but then have to take it home with us. (We try to visit a few hours almost every day).
My Aunt in MC had dentures and would take them out to eat, but wrap them in a napkin and put them on her tray so that it looked like a used napkin and they'd get thrown out. Another set she hid in her room.
I'm wondering if installing a camera in her room to see where they are going may be possible?
IDK what a solution would be except what you've already done.