My sister has a private babysitter as well. The babysitter started making lists like that and she suspected that the babysitter's kids (teenagers) were eating the food she sent. Now she packs a lunchbox each every day and sends milk at the beginning of week, she also makes sure there's a uht milk (she buys it) at the babysitter's house in case the milk runs out or she doesn't have time to grab one on the way etc. It's working really well and saving her heaps of money. Maybe that's something to think about.