It does look like 3 blacks and a blue, at least right now. There is no way to sex them on appearance. They will have you guessing for months!!!!! The blue should not be used for breeding. You want to improve, not introduce faults/DQ's.
Why should the blues not be used for breeding? Is blue (or any color dilution) a fault? Does the dilution gene act in birds the way it does in dogs? Can they develop poor quality feathers just by virtue of being dilutes?
These birds are not for show...just pets/food...I'm just curious.
TIA!