My first recommendation would be for you to relax because children pick up on our stress. Babies don't starve themselves but they can be very stubborn. Are you sure she's losing weight? If so, that's probably very temporary and she'll learn next week that this is her new life and daycare is going to be her new reality whether she likes it or not.

I understand why you are upset but keep asking the parents what they want you to do. Keep trying but relax.