Sounds like you guys have silkies.. I'm no expert, but it is my understanding, silkies can have the extra toes, or not, they are still silkies. They can also have the vaulted head, or not- still silkie. I think they do have to have black skin and of course the silkie feathers, but some traits like toes and vaulted heads,are not always present. I dont know what the breed requirements are for show birds though.
I have a silkie that has extra toes on one foot, and not the other! Some of my silkies have the 'big top' heads, and some dont, but they all have the special feathers and black skin. Theyre all hatchery stock, for whatever thats worth.