Of course, you have to sign an agreement and have a clear responsibility, otherwise you will be in trouble if something happens to your child. You'd better find a lawyer and carefully draft an agreement for you.

Regarding the refund, I think we can follow the example of the hotel. How many days in advance can you cancel without charge, such as at least two days, because you need to prepare meals. Buy according to the number of people. If the children don't come, they will lose money.

There are also photos of people who ask their parents to pick up their children, so they should be seated accordingly to avoid the children being picked up by people they don't know; Buy a lamp with real ultraviolet function and turn it on for 30-60 minutes every day after the child leaves, so that parents can rest assured, but be careful not to let the child touch it. This thing can be very dangerous.

I don't know anything else and I have no experience. I just want to help you.