Welcome back. I guess you know by now, never buy a pup sight unseen regardless if your breeder recommended them. Your pup is adorable and you love him, that's all that matters .
In all honesty, IMO, he dogs not look like a yorkie even tho he has mixed colors. Pure parti yorkies and traditional color yorkies the shape and look of the face are the same, I don't see that in your Parti yorkie, he is more likely a yorkie mixed with another breed.
(members of YT please chime in, what are your thoughts, pure parti yorkie or mix breed)
If you're curious as to what breed he is, you can do a DNA on him. I have read Wisdom panel is pretty accurate
DNA Wisdom Panel www.WisdomPanel.com
If you decide to do the DNA please let us know the results.
I know you love him regardless, if it were me, I am a curious person, if it were me, I would want to know just out of curiosity.