If Skye's markings are dilute that could be the influence of any number of other mutations. Could be some Recessive Silver, Dominant Silver, Lightback or even a single factor Florida Fancy at work there mixed in with the normal gray and the pied. Check out this link to get a general idea.
http://www.efinch.com/varieties.htm
How much of a breast bar does he have? Is it dark and pronounced or is it barely visible? Skye's pied markings may or may not carry through to his offspring. And Sydney won't carry the fawn gene through to any male offspring that she might produce unless Skye has it in his genetic background.
Actually Skye and Sydney's heritage will have a lot to do with what type of chicks they produce. So it's hard to guess what could result without that information. We actually have had a breeding couple or two similar to Skye and Sydney and they have produced all kinds of chicks. They most prevalent though are definitely fawn pied hens. But then we have had everything from normal grays to gray pieds with even some Chestnut Flanked Whites pop up unexpectedly.
Again the amount of pied depends on what their parents were. We've had pied parents produce chicks that didn't display any pied markings, but they most likely will carry that trait along. So if Sydney is carrying pied in her line the amount of pied will be increased in the chicks that she and Skye produce.
My best guess would have to be fawn pied hen(s), probably a gray pied or two (male and / or female) and maybe a fawn hen or two, and / or some normal gray (male and female). Although chances are most likely they'll pop out something totally out of the blue, depending again on what is behind the dilution of Skye's markings.
Keep us updated on what happens.
