I would not use them if you want to breed pure ameraucanas. They may well carry the yellow gene that is now hidden by the white.Many pages ago, I posted bbs chick pictures with yellow feet. They are almost mature now. The 2 pullets have white skin, but the cock bird has yellow skin. I know some will say get a new male, but if I work with what I have, what will I get? which is dominant, white or yellow skin?
Spend your precious time (and $$) on some quality chicks/birds and save yourself big headaches later.
Good luck!