The breeds they have come from are
Light and Buff sussex
Plymouth Rock
Australorp all large breed
Maybe also Araucana and Wyandotte but not 100% sure of those two![]()
Some of those breeds have fairly large combs even for the hens so it could be easy to be fooled.
Wait for the mature saddle feathers to show. With the exception of the rare, "hen feathered" breeds the saddles don't lie.