Ahh I understand what you're asking...
I'll use the example of a Killer Queen Bee like you labeled, a Super Pastel Butter (or lesser) Spider. This is commonly refered to a "4 Gene" animal in the trade, because the alleles it carries that are not "Normal" are:
Pastel - Pastel - Butter - Spider
Okay, for simplicity I won't explain the difference between alleles and genes... as techinically some would argue this is a "3 Gene" animal having having the homozygous form of a gene (pastel) but we'll save the nitty gritty stuff and try to answer the meat of your question.
The first thing to consider is: Are the genes that compose of this animal's genetic makeup Dominant traits, Codominant, Recessive, or a mix? This takes a little practice in understanding the morphs, but you'll catch on very quickly. It just so happens that the Killer Queen example we are using is composed of codominant and dominant traits, making things easier for us:
Pastel - Codom
Butter - Codom (or lesser)
Spider - Dominant
Okay - here is where I may lose the crap out of you... LOL!
Here's how co-dominant traits work... we'll use the Butter as an example:
A codominant animal is one that has an allele for a trait that is not "normal" or makes for a wildtype phenotype of the animal. A simple codominant animal like the 'Butter' will carry an allele for the Butter phenotype and an allele for the Normal phenotype.
There is the homozygous (often referred to in our hobby as the "super" form) of a particular phenotype/trait/mutation. The homozygous individual in this case would be the Blue-Eyed Leucistic, the heterozygous individual is visibly different that the normal - making it a Butter, and then you can have the Normal/Wildtype individual from alleles on the same gene
Unless you have a Blue-Eyed Lucy (BEL), there is a chance that that the alleles will match up to produce Normal individuals who lack the Butter allele all-together. They will never get it back, its gone. I'll do a brief rundown:
Lets make a co-dominant Butter individual have the following representation: Bb
The BEL, homozygous form will be : BB
The Normal individual shall be: bb
If you cross a Butter [Bb] with a normal [bb] (using basic Punnet principles) we get the following outcome:
50% Bb , 50% bb . So you will end up with 50% of the offspring who do NOT carry any form of the Butter allele anymore. Any offspring they produce in the future will not be Butter unless they are bred to another Butter or Super Butter (BEL).
Now, Let's cross a Butter [Bb] with another Butter [Bb]
You now have a shot at the homozygous trait for the Butter gene, the 'Super Butter', or 'BEL'[BB]
You will produce 25% BB, 50% Bb, and 25% bb. There is still a chance of normal offspring who lack the butter gene alltogether, but you have a shot at the homozygous super form of the mutation and increase odds at the heterozygous 'Butters'.
Only when you have a Super Butter, homozygous form of the gene [BB] can you guarantee no normal offspring. All offspring will have the Butter allele. The percentages of how many are Butters vs. BEL's depends on what it is bred to.
Dominant animals in this case, like the Spider morph, behave essentially the same way. Recessives complicated things, but we'll save that for now = )
SOOO:
In order to produce a Killer Queen (Pastel - Pastel - Butter - Spider) you need to have at LEAST that many alleles from the parents that are no "Normal." Furthermore, the mother and father must each carry at least one allele for the Pastel trait, otherwise you cannot create the homozygous 'Super Pastel'
One way you might go about doing this is to cross two "double codoms" as commonly refered to in the hobby. For example:
BumbleBee (Pastel Spider) X Butter Pastel
The odds of producing a Killer Queen from this pairing is only a 1/16 (6.25%)chance per egg, so odds are fairly slim. This is part of the reason why these morphs are so expensive and make for great breeding tools - the more "Normal" alleles you kick out to replace with desireable morphs, the better the odds of producing offspring that are awesome.
You double your chances by adding another pastel gene in there, for example:
Killer Bee (Super Pastel Spider) X Butter Pastel
This gives you a 1/8 shot per egg at the Killer Queen (12.5%).
Have I lost you? lol... It can be confusing, but with time it all works out
Again, I'm sorry if I used alleles or genes interchangeably, it seems to be a common trend in this hobby to make things easier for descriptions. If you can make both mommy and daddy super pastel somethings... you double the odds again. Basically by forcing the Pastel Gene to show its homozygous form in every baby, you are guranteed "Super Pastel...something" That other trait can come from mom, dad, or both!
Example: Killer Bee (Super Pastel Spider) X Super Pastel Butter
Now, as described earlier... Because we are crossing two homozygous super forms of a gene (Pastel) EVERY baby will be a Super Pastel...something. You will get 25% Super Pastels, 25% Super Pastel Spiders, 25% Super Pastel Butters, and 25% Super Pastel Butter Spiders (Killer Queens).
