you have a great variation in phenotypes, so obviously not talking about homozygous lines. Plus, incompletely dominant mutations are renown for showing variability in expression. So I don't think it means much at all the variability in the amount of phaeomelanin on the wings.
Both eb and e+ have dark undercolour, & if you have het. eumelanin restrictors with silkies, this undercolour is more visible than normal feathered birds (simply due to the hookless feather structure sitting more open, not tight against the body). That's all I was saying.
This is eb/eb hen without eumelanin restrictors:
An old photo of a Partridge Silkie hen I had (no eumelanin restrictors)
A couple of silkies (probably eb based) - het. for eumelanin restrictors (crossing lines):
The following roo going by chick down in his offspring was probably Db, not Co:
Your chicks don't look typical eb Db, but maybe Co in there (more eumelanin in chick down)?
A e+/e+ silkie crossbred pullet I had:
Read PB&G about e+ & eWh salmon pigment in hens. Apparently its a different phaeomelanin pigment compound to the other phaeomelanin pigment in chickens (ie that's one way to tell the difference - chemical tests).