Primary, secondary, and tertiary are separated from each other... If you scroll through the color choices like in the AH or anywhere, how far apart the colors are placed (between primary mom and primary dad, etc) means the baby's primary can be mom or dad's primary and any color literally that are listed in between. It has nothing to do with actual color mixing unfortunately. :s
So if the mom had a Leaf primary and dad had a Banana primary, then the baby could be Leaf, Spring, Goldenrod, Lemon, or Banana. Spring and Goldenrod are pretty ugly colors. LOL
if mom had a white primary and dad has a white secondary, those two whites aren't affected by each other at all, because they're not on the same level.
primary is body color
secondary is wing color
tertiary is special genes color (circuit, gembond, etc)
and in terms of genes, this is a good guide for probability
http://flightrising.com/main.php?p=mb&board=gde&id=1123974