J.T.
B.,
Must be frustrating. I also work in a daycare and the first thing I would suggest is talking to the parent. If you do not have their backing or support - they will go home and eat dinner and/or breakfast with the family and it will be a lesson in futility! I would find out if they are experiencing the same thing and then work with the parent on changing the behavior. Especially at 3 yrs old, you don't want the little one going to the mom and saying that Miss B. told me I was rude when I eat (giving their mom the shortened version) and have any questions arise.
Good luck!
J.