Just a note: The polydactly gene is Semi Dominant, so some will either inherit the trait, or not inherit it.
(Some Pure Bred silkies can actually be born with 4 toes instead of 5)
Also another clue that your Barred Rock has fathered some chicks, is the chicks should have some form of a headspot.
Silkie Feathering is Recessive, so it won't show in the first generation.