In cases where there is not much freezer space, we use the owner’s items first and simply replace them with the same items for their return. The fridge space, normally the owners want us use as it will perish before they return and they do not want/expect that to be replaced.
I have posted before that I simply ask but I would like to add that it is best to give the HOs reasonable notice so that they can run some food down
I’ve never noticed a checklist… Guess I’ll go have a look.
Food is always difficult.
- Our freezer is tiny, even with a second “mini-freezer”. But I do leave them room in the fridge for their items.
- I’ve left food in the fridge for our sitters only to find that they bought their own (for instance, an unopened litre of milk, which they went and bought their own (identical) litre of milk). By the time we got home, the food we left for them had spoiled.
This makes me laugh because THIS is my freezer. And no, I don’t live in a college dorm, I live in Germany. When we moved here from the US I had to completely rethink meal prep and grocery shopping. When the pandemic hit and we had to stock up on groceries, we ended up buying a three-drawer stand-alone freezer…which we now use for our dog’s food. We feed him a raw diet and I prep two weeks worth of meals at a time so that freezer is now filled with 28 1-liter containers and a few extra packets of raw parts. 
It is what it is.