Speaking from experience they will be fine, their development and instincts are close enough that they should integrate with little issue. Just check on them often and if any seem really persistent or aggressive give it time alone and it will rethink itself. Chickens have group instincts. My dominique was an eye pecker when I got her as a chick. A few times of being alone in her own box where she could hear the others but not peck them made her feel lonely enough she stopped trying to peck out eyes (she was in the second youngest group I brought in as day old chicks into chicks 3wks older). Other than her pecking eyes they all meshed really well. I did and still do handle my chickens (even chicks) often so that may have helped. I have young kids in the home so I wanted to make sure that the birds I had were easy going to being handled. Kids are unpredictable after all.
