Homecooking is ok. It's not as easy to get right as the internet makes it sound.
Food has been switched too quickly it sounds like. And some foods have been iven that would make any dog have diarrhea (i.e. tomato).
Pick a food. Stick with it.
Since they are sick today and you can't go to the vet til tomorrow, I'd personally feed something bland. It sounds like they are sick on the Orijen (probably because the switch was too quick).
It sounds like a food problem, but because they both get it at the same time, other causes need to be rule out, and only a vet can do that. A day or two of diarrhea for a Yorkie can be extremely dangerous (depending on how many times they go and how much wter they are drinking).