I didn't answer your question very well, you are correct in that all these different patterns are just being recognized because of all the cross breeding of the colors. The lethal white syndrome is just because overos carry a gene that causes lethal white, if you breed two carriers together you can get a lethal white.
My genetics book says that crossing the different patterns destroys the integrity of each marking, that's why professional breeders don't do it.
Your post was fine, you answered what I was asking:)
So professional breeders, would they usually bred a toby to a an overo, or do they breed to toby's and hope for an overo?
Becky