Don't know for sure. You will need to contact AKC
www.akc.org and speak with the registration person.
doing what is best for your dogs has very little to do with a registry. It has a whole lot to do with how knowledgeable you are with Yorkies. The training, studying, and mentor you have in place to know what you are doing with respect to breeding.
And fyi it is definitely not recommended to breed a female every heat. If that is what the two litters a year means.
If you want to breed do it right. Champion your dogs. Do ALL the health tests, and know the health problems of the lines you are breeding into.
If breeding is done right, there is little if any money to be made. Of course as you should know the market is a bit soft right now for sales of purebreds.