Oh My
I hope this is just a misunderstanding that can be easily resolved.
You said in your other post that your vet said that tiny ones are okay to breed but please get the opinion of another vet before going forward. I know that you've bred other breeds before but Yorkies do present special challenges and not all vets are knowledgable in that area.
I would also get the opinion of some of the other breeders on here and get their take on the situation. I know there is a lot more than just weight involved in deciding whether or not a female is too small and there are some really good threads on that in the breeder section.