First and foremost, welcome to YT! And, congratulations on the new editions!!!
I happen to know first hand that notwithstanding the usual genetics defects of standards, i.e. shunts, bad knees, etc. - Chocolate yorkies are just as healthy as standards. Based on all the literature that I have read since being adopted by them (just check my photo album
) and further confirmations by my Veterinarian, only the little ones that are born blue give reason for health concerns.
Wishing you the best of luck with little ones!