J.P.
Have someone else offer it to him while you are out of the house. He won't starve himself, but he may go on a bottle strike. Keep what you are doing though, and he will either wait when with the Nanny, or start taking the bottle/sippy cup (if a sippy cup, try it yourself so you know how easy/hard it is for him to drink from it - the Nuk seem the most natural to me).