I feed my dogs only homecooked meals with added supplements, no dry or canned food.
I have heard of many foods that people have fed their yorkies with success including Innova(
www.naturapet.com), California Natural(
www.naturapet.com), Canidae(
www.canidae.com), Chicken Soup for the Dog Lover's Soul(
www.chickensoupforthepetloverssoul.com), Solid Gold(
www.solidgoldhealth.com)...
It sounds like you're feeding high quality foods already
So, you might just try getting one of their canned foods