We had two grown Yorkies and added a little female. Two months later we added a little male. Bizzy Bee was quickly trained and used the dog door easily. Jersey Boy was a boy and came with his own instincts to "mark", so we immediately adopted belly bands. I kept him in bands until all of our females had gone through a heat because he kept trying to "mark".
Then to my surprise, I just started leaving the belly band off in the morning after his first outside time...and it appears that he is house trained! Go figure! So potty training two can be done.
The great benefit is that two are more than twice as good as one -- more fun, more playful, better companions. They are such a joy to each other, running and playing and jumping and exploring together. This way they leave the older yorkies alone and chew on each other.
If you have the time to put into the potty training, I highly recommend two yorkies!
