Here is some info on Biewers and Partis:
http://www.yorkietalk.com/forums/bre...formation.html
Basically, you can trace them back to originating at the same kennel.
Yes, you can DNA test a dog - you can buy the Wisdom Panel and have it done; they're very accurate and detailed.
A biewer is the result of 2 biewers mating; a parti is the result of yorkies. Mating a biewer w/ a standard yorkie is looked down upon by some and the result is often *not* considered a true Biewer, although some breeders will sell them as such.