Have you asked yourself why you feel like you need a third...since you are still in the midst of the newness of your second?
I can empathize with your desire but, I'd probably pass on the third especially at this time.
After fostering Yorkies and seeing all the health problems that accompany even the best of Yorkies...unless you have a savings set up of at least $1000 for each one plus insurance...I'd say hold off on that third

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Sorry to be a downer...but, I know that feeling especially after browsing around here on YT and seeing all the new lil' ones...it can get tempting