I got 3 Super Blues, 2 pullets and 1 cockerel - now 3 weeks old. Based on the behavior (with a Welsummer that was supposed to be a pullet, not a roo) and appearance, I believe the gray is the cockerel and the 2 white ones are the pullets. Their down is very light and very fine. The one that had some black 'smudge' marks (far right, 1st pic, far left 2nd pic) got picked at probably because the others were 'cleaning' her- and that thin light down shows a lot of skin, so the resulting red skin created an even bigger target. Vasoline helped deter the 'helpers' and now she's growing in feathers. I suggest keeping an eye out, especially if you get one with black smudges. Enjoy your new chicks!
Thanks for the pictures, they're lovely! And thanks for the heads up with the pecking on the spot.