I would suggest keeping them separate unless you raise them together, letting them mingle will create trouble in all groups, ie pecking order, once you allow them to settle things out, you should leave them that way or they will have to re-establish pecking order in their own group each time they are separated and then again when allowed to mingle again, I have tried to do as you suggest but there is always conflict between flock leader and sub roosters in the combined group, although when separate the sub roosters become their group leader again, this back and forth will only make for constant ranting/conflicts between them, the same goes for the dominant hens of each group, it will effect egg production in the layers and reduced growth in the meat birds and then you need to think about possible injury's from the conflicts and medical attention relating to this. Also if a member of a group gets sick, if they all mingle you run a greater risk of infecting the whole flock and not just the one group. Some one else may have a different view on this but every time I have tried to co-mingle mine, egg production has suffered and there was a constant conflict going on in the run, once a chicken gets injured or bloodied, the others are going to team up against it as they see this as a weakness, a threat to the survival of the flock.
