Do you or did you ever live in Florida? I knew someone there that use to breed small ones, but this was back before 1989. Just remember not to keep your yorkies outside too. They are inside dogs. They don't do well out in the weather - too warm, etc.. They like it cool. I would check your females out by a vet that specializes in smaller breeds to make sure they can deliver on their own (naturally). Yorkies do not do well with c-sections (anesthsia). Have you had your yorkies tested to make sure they are all sound, before breeding? And I would keep mamma and pups in my home until they are at least 7 weeks to be sure they are all doing fine. Two weeks is just not enough. The pups also need a lot of interaction with humans and they need to hear the different living sounds us humans make, such as using the vacuum cleaner or washing dishes. This is to get them adjusted and happy, so they will do great in their new homes. I would keep the pups in my home until they leave at 12 weeks. They are so cute and funny at times. They are a real joy and worth every poop mess they make. I also enjoy all the kisses and that puppy breath.
Best of luck to you.
T.