You can single mate your male to the females of best type and mass and then you can choose a male or two from their offspring to replace the original male if you need to. Single mating allows you to pinpoint which pair/mating produces which chicks so you can mark them accordingly. Offspring from pair A (your male x female 1) can be mated to offspring from pair B your male x female 2) and so on and so forth. Half siblings are fine to breed as long as you arent doing it every generation. You can even mate a son back to his mother, or nephew to aunt. There are many ways you can breed within a line. If your male doesnt turn out so good Im sure you wont have trouble finding another male later on when your pullets are old enough to breed.