My husband and I are building a hoop house to hold 15-20 birds. We already have 5 RIRs (9-weeks). I would like to get several different dual purpose breeds but my husband thinks we should get all RIRs so they won't pick on each other. If I introduce several young birds of different breeds to the RIRs, and they have a large coop, enough nesting boxes, and a large run, what are the chances of either the RIRs dominating the new birds or of the different breeds picking on another breed as they mature. We've always had pullets of the same breed and/or same age (but no more than 5) and very little pecking. Sounds like a basic (stupid) question but I really need to know what to avoid in this expansion process! TIA!