Wow! Chocolate in the morning? You've got to be kidding me! I have a child who often comes unfed or with food in his hand. If he has food in hand he goes directly to the highchair because thats where we eat food in this house. If he hasn't eaten at all, I let mom know that snack time is at 9:30. But I never offer to feed him.
I think you're right about the final notice. Giving a child chocolate before they come to daycare is just not right, and I think having them walk in with candy is disrespectful to you and your daycare.
I was having trouble with one parent bringing food that wasn't Peanut free and I have a son with an allergy, so I put a sign in my front hall. You could try putting a "no candy" sign by the front door. That may give them the hint.
Good luck.. I hope it works out and you can salvage the family. It's such a shame when you have to transistion another one in.