Even if breakfast is part of your agreement the parents should be giving the child a full bottle of milk before he arrives to stave off the empty tummy and reestabalish the sugar balance etc. It will go a long way to making him happier in the morning when he arrives.

Alternately he eats when he does arrive but his meal is strictly child fed - dry cereal, pieces of toast, and then WHEN you have time you give him fruit such as applesauce so you have some time with him and then he starts his morning nap or plays in a confined space while others eat and then goes for nap - ie doens't get to eat twice nor spend all of first part of the day in a highchair.

Think mom is just being lazy here. If child will eat cheerios for you when he first arrives then he is hungry enough at home to be given some food even the cereal there so it keeps him ok till breakfast at your house.