So all three ISA Browns are the same color? If so ... They are all the same gender.
The other three breeds you have are not "sex-linked" ... If they are varing colors ... They must not be purebreds.
The Isa Browns should be easy to confirm NOW, as they are a sex-linked chicken, no need to guess at flight feathers ... ;)
From - https://www.backyardchickens.com/a/rhode-island-isa-brown-hybrid-cross-between-rhode-island-red-female-and-rhode-island-white-male
So ... What color are your Isa...