My guess is that the first chick is a "black" laced red rooster. 2nd picture splash pullet and 3rd picture a splash rooster because of some solid red feathers on the shoulders. Good news is that if you breed your black laced red rooster to your splash pullet you will get 100% blue chicks.
I am looking at the combs, the head types and body language. Your black laced red chicks comb is turning red and he has a more upright stance. The pullets show better lacing than the roosters at an early age. Note the barring and some solid shoulder feathers on the rooster chicks. The eyes of the rooster chicks are rounder and have a surprised expression, where as, notice how the pullet has a softer look to the eyes and keeps her head lower. The roosters stand up and are the look outs for the flock. I also see wattles developing on the two roosters. Usually the roosters legs are thicker.
I always keep pictures of each hatch of chicks to refer back to. After a few times you learn what to look for.
Thank you for your reply. Could you enlighten me on how to tell if they are pullets or roosters?