It seems that a sound they do not like is the key to solving this problem unless you have more stubborn dogs. I found a website that has some tips.
http://www.dogpatch.org/sheltie/barking.html I'm going to trying the throwing a can of method. You throw a can of coins and they don't like the noise so they stop barking. I hope it works. They don't really listen when I say no barking. I'll let you know if it works. Then I'll have other problems to work out with my maltese, he likes to destroy stuff when he's unsupervised or when we go out and the yorkie joins in. We saw couch stuffing in both of their poop. My yorkie doesn't do it when she is left alone....but joins in on his mischief.
P.S. I tried shaking the can 1st that didnt work they still barked but when I threw the can that had a much better effect. Seems to be working, the bad thing is I have to do it everytime they bark.