I have three yorkies but don't work. I think if your other two are fully trained you wont have a problem I got my third who was an adult dog(16 mos.) when our second was still a pup and not trained. The adult dog hadn't been trained when I got him and it has not been easy with two of them not housebroken and marking.
Thank God for belly bands. My oldest yorkie is a barker and is trying to teach them that too. I'd do it all over again in a second though.
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"If you have men who will exclude any of God’s creatures from the shelter of compassion and pity, you will have men who will deal likewise with their fellow men." — St. Francis of Assisi, 1181-1226