In terms of mil sins this is extremely minor but I struggled to contain my jaw drop when mil mentioned this.
Mil babysat the other evening and stayed over. All fine. The next day she mentioned that she had fancied a choccy while babysitting so she had opened a Christmas hamper that Dh's dad had sent us (divorced many years) found a box of chocolates in it, opened the pack and eaten 3. We were saving it for Christmas! Aibu to think this was kind of cheeky?! She had access to fridge, cupboards, pal. P plenty of bread a d etc