Sometimes a picky eater is created by the owner. Unintentionally, of course. But a dog is very capable of piecing together that refusal to eat = extra yummy things!
As long as there isn’t any health concern, a dog won’t actually starve themselves when there is food present. Typically when someone says, “My dog will only eat if I do this” it is because the dog learned how to condition their owner!
Why would they choose plain old dog food when they can just skip a meal and get rewarded for doing so?
My advice would be to stick to one dog food, and just add water if he skips a meal. He will eat eventually, don’t worry. And if he doesn’t, then he should see the vet – not get extra food added. Don’t let him fool you 😉