yeah i wanted to suggest lor, if celine's boy associates macdonalds stuff (box, etc) with food he can eat then how about trying that.
Get a box, with macs nuggets, feed at home. then slowly replace it with perhaps home made nuggets one at a time.
i had a client b4, he refuse to drink water. Will only drink coke from macs. So we tried, get the cup and straw from macs and put in plain water and he drank.. then slowly we show him, we pour the 'coke' from the macs cup into another cup. (so he thinks its the same) then he drank the 'coke' from the other cup too..