Coming from a very strict clean your plate family, i still have issues with this as an adult! We have decided not to do this with our children, but hate wasting food. Our back up plan, as we both HATE wasting food, we give it to the dog! There is no waste, literally she will eat anything except lettuce and mushrooms, and everyone is happy! I know this doesn't work for everyone, but the conscience is clear at our home :-)
Sorry if I haven't gotten back with anyone via PM. Still learning the iPhone app and not very "techy".