Seems like in theory this is not possible. However, I ended up with a blue mottle out of two black mottles......and a blue mille fleur out of a black mottle and buff (I think). These were not birds I bred, but birds another BYC member bred and ended up with and I am just curious. I thought you had to have blue or splash x black to get blue? How would you get a blue mottle out of two black mottled birds??? She does not like blue mottles and so has none on the property.......and her birds are in breeding pens that are covered.