I am not sure why this information has not been given yet, but there is absolutely no chance of your F1 chicks to have blue/dark shanks.There are 4 chicks hatched so far. One of chick hatched more than 24 hours so I have no choice, but remove from the incubator. I think the chick has pea comb. It is too hard to tell what color of the leg will be until next 1-2 weeks.
You see white/yellow shanks are due to the sex linked dominant dermal inhibitor(Id), for blue/Slate shanks you need id+(and the white skin autosomal dominant gene W+)
Your rooster is Id/Id your hens are id+/- the F1s will be Id/- for the pullets and Id/id+ for the cockerels