Last night on the dog show when the Silky came out they did explain that the Silky breed was made by breeding the Yorkie Terrier and the Australian Terrier.
So that is why the Silky looks like the Yorkie not the other way around.
Also, depending were you got your dog we all know story's about the Pet Stores dogs and puppymills. Well, here's my latest one I heard.
I met this girl another Yorkie owner, she saw I have a Yorkie and a Maltese and said " Oh, you have Maltese my friend went to buy one at the pet store were I got my Yorkie, when it got bigger it turned out be a Bichon with papers and reg. as a Maltese"