they well be find they all are close in size. just when you first put them in their coop and packing order will be find for the first few days but other htne that they should be just find.
I would do the same my cochin hen was a bully as a chick, But your leghorn are small and should get to grow a little then put togher or slipt the brood in half with hardware cloth so all the chick still see one another after a few take the hardware out.
Same here. During the growing my runner ducks live in the garden to eat the bugs and not the all veggies.(unlike my chickens eating everything in the garden)