What are you currently feeding the lil guys?
We fed Innova to Oakley but she still had the staining on that. Honestly with white faced pups, you're going to want to wipe their eyes as often as you can, gently, w/ a warm washcloth, but as far as good quality food, that is a kibble, I did really like the Innova BUT it was bought out by Proctor & Gamble, which may or may not change the quality (its likely it will).
You want to be absolutely SURE that the food has NO BEET PULP. If the food has beet pulp, it very likely may cause staining, esp. on such fair faced sweetie pie babies

If their current food doesn't have beet pulp, corn or wheat or soy may be a cause as well.
I really like the Fromm all life stages kibbles -- they have a grain free one called Surf n' Turf that is itty bitty little kibbles, like smaller than tic tacs. It has a good variety of proteins in it too, besides just chicken like many dog foods have. Its pretty affordable, especially with the small amount chi puppies eat.
Hope you find something that works for you sooner than later