I have an old grouchy lab mix that does not like anyone that came along after her except the cat. Good Luck iheartyorkies! What has helped tention in general in our little abode is playing with one for 5 minutes, playing with them together, playing with other for 5 minutes. I walk my two non-yorkies separately too. Luca Dean (my yorkie baby!) doesn't seem to enjoy physical exertion.
And comgrats on te new one! Rosie looks happy! and so does your new pup! And your son too(?) !