What you need is an enforcer hen. I have a Serama Hen that hangs out with the silkie hens and Silkie rooster. She is funny we have a cockerel 4 months of age (in the background) and if he tries to join the group she chases him all around the yard. It’s the funniest thing to watch this tiny chicken sending the boy packing that’s 3 x her size.
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But all seriousness, something’s to think about are what is your winter space going to be like? Will they all have space to work out any differences. I made a big mistake last fall and had late hatch leaving me with grow outs that came of age at the end of winter. I ended up with 8 boys it was like romper room in the coop, no serious fights but enough stress. As soon as it got warm enough I started free ranging the boys and finding them homes. But I learned my lesson. Just because they are Bantam doesn’t make them any less likely to fight. Some Bantam breeds are very territorial and have napoleon complex. Keep a close eye on the flock the next few weeks and months.