I feel when you deal with these splits it should always be a lavender male over split females. This makes the sex-linked silver/gold s-locus gene work in your favor.
Can you elaborate on this John? I've got a Lav cock over split hens, and have had a few very yellowy downed lavender chicks pop out. What does that imply?
I guess because all the text was in the quote box I missed the questions (I modified it).
Since all the pullets will be the same as their sire at the s-locus (either silver or gold), due to the sex linkage, when making any outcross with different Ameraucana varieties I try to use the cock of the variety that I'm working to improve. Now if the cock isn't pure for silver or gold it can be a problem, but I'm assuming he is pure for which ever one he should be. The next year you would only use the pullets from the outcross, so when breeding lavender to lavender/black splits/crosses always use a lavender male over the split pullets and cull all split cockerels.
This is basically the same procedure I follow when outcrossing LF blacks to another variety to improve that variety...buff cock over black hens, silver cock over black hens, etc. Use only the F2 pullets the next year with males of the varieties they are split/crossed with.
I'm not sure on the yellowy looking chicks. They should look just like an E/E black chick with lavender replacing the black. Here again, I say uniformity of day-old chicks means uniformity of adult birds. Once you figure it out you can start culling as they come from the hatcher. For me the good ones go into the brooders with chicks for me to raise or to fill orders and the others go into my "reject" brooder to be sold locally as backyard chickens.