I agree with gracielove completely, except that it wasn't put as forcefully as should be.
There is no Breed, or age of any of the K-9, which has the desire to be the Pack Alpha more than a Female Yorkshire Terrier. The only thing that can completely control a Female Yorkie, is another Female Yorkie !
Her persistence and tenacity will eventually overcome your other Dog's objections to her authority, and she will "allow" it to "step forward" only under certain circumstances, probably when the Pack needs defense (because of it's size).
I'm not sure that I would so quickly blame her previous owners, given that they may have understood her "nature". Probably she was the only female in her Liter, and its just a guess, but, I'm thinking she was not allowed to stay with her Mother very long. These two conditions have a tendency to produce a rather "strong" instinct for Leadership.
You may need to re-think the "Order" of things around your house, and yield to you being the Pack Leader, and allowing her to be the Pack Alpha.
Not all appreciate the difference.
And, establishing that "Pecking Order" depends on her evaluation of your ability to lead her. There's going to be one Leader, and one Second in Command, and she's gong to be one of them.