Hi and welcome to YT
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Yes, you should most definitely get them *all* fixed so that you're not bringing any more surplus animals into this world. Are you breeding for a reason, or were these all "oops" breedings...? Either way, unless these are truly show-quality yorkies, I would not recommend breeding these kiddos, lest they just end up in a shelter...which happens to 7-8 million pets a year now (3-4 million are killed/euthanized every year). In my opinion, breeding should only be done very specifically...with a mentor involved, all health testing done to the dogs prior to breeding, and only should involve the very best example of the breed.
Do the dogs have names?