Looks more like just a white pommie...and people have been x-ing pomms and yorkies for a while now. Part of the "Designer dog" craze.
This isn't a white yorkie, I would think the closest thing to a white yorkie would be a Biewer with very little markings.
Why did you breed your maltese/yorkie? The dog shelters are overloaded with dogs just like these that are beeing PTS to make room for more.
sad but true.
JMO