They're unlikely to be actual Araucana mixes because that's a rare and unusual breed, or even Ameraucanas, which are not *as* rare but still unusual in hatchery birds -- but Easter Eggers are often sold as "Americanas" and people get confused by the frankly deceptive naming.
If they hatched...
How old are the birds in question?
If you're not wanting to raise chicks and absolutely have to be sure of the sex, then ideally, you'd want Point-of-Lay Pullets -- young females who are of age to start laying.
If you buy mature hens the stress of the change is likely to throw them into a...