Kitty has a "pencil box" at school. One type of thing she has in there are animal, multi-part erasers. They have been disappearing or she sees them in the hands of other kids in her class. The others deny that they are hers, but they look the same. Hmmm. Other items have disappeared from her backpack too.
She and Dolly have been discussing this. I don't see the need for much discussion. Get a little lock for the pencil box and the backpack and be done with it.