That is an interesting article in the link but you may be missing a basic understanding of how egg color works.
You are dealing in gene pairs. Ignoring the sex linked genes (which is legitimate from a basic understanding), a chick gets one gene from each parent at each gene pair.
The base color is set at one specific gene pair. The gene is either a blue gene or a not-blue gene. To keep it simple a not-blue gives you white. Blue is dominant over white. If one or both of the genes at that gene pair are blue, the hen lays a base blue egg. If both are white, she lays a base white egg.
Brown and green are simply brown laid on top of a base white or blue egg. There are a lot of different genes involved with shade of brown. That's why you can get so many different shades of green or brown. Some are light tints, some are deep chocolate brown. Welsummer and Marans often lay dark brown eggs.
An olive egg is a deep chocolate brown on a base blue egg. It does not matter whether that olive egg has one or two blue genes as far as appearance goes, but it does matter as far as inheritance goes.
When you cross a Welsummer or Marans with a hen that has the blue egg gene and get an olive egg layer, that pullet has one blue gene and one white gene. She will give about half of her offspring the blue gene, the other half get the white gene. Maybe this will help you visualize it. Consider the capital "O" stands for the Blue egg gene and the lower case "o" stands for the white. For simplicity assume the blue egg gene contributor has two blue genes. It does not matter if the mother or father has the blue or the white as long as you have one of each.
So you are crossing a not-blue chicken with o,o genes at that gene pair with a chicken that has O,O so the offspring will get one of each (O,o). The pullets will lay a blue based egg.
When you cross two of these offspring they both have O,o. About 1/4 will get O,O, about 1/2 will get O,o, about 1/4 will get o,o. So about 3/4 of the pullets should lay a base blue egg.
If you cross an offspring O,o to the parent with the o,o (no blue genes) you get about half that will get O,o and half with o,o.
The brown genetics are a lot more complicated because there are so many gene pairs involved but the basic idea is the same. If you cross the offspring back to the one with the chocolate brown genetics you enhance those chocolate brown genetics. If you cross the offspring back to the other parent you decrease the influence of the chocolate brown genetics. You don't necessarily get consistent results because each gene of those brown gene pairs are handed down randomly so you can get a wide range of results, but your trend should be in the right direction.
I don't know if this helps you at all but good luck with it.
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