I don't think they will miss each other. But a lot depends on the circumstances. So
Do you:
- have measurements of the coops/ runs
- do you have hideouts, and clutter in the runs
- do you have multiple feed bowls
- do the flocks ever interact as in a free ranging set up or are they next to each other in their own pens?
And to make sure I under stand it, you want to put the 5 older Orps with two younger Orps and a Orp rooster - so 7 birds. I think that if you move the old girls into the young groups coop/run, it should work pretty well, seniority should be about equal with home turf.
I would put the young birds out of the set up, and put the 5 old ladies in the strange coop, for a day, and let the trio back in at night. This lets the birds explore the place without a confrontation. Get it figured out, then the urge to roost is about equal with the urge to fight, I would expect this group to work well, with a minimum dust up, but truthfully anything can happen.
I am a bit more concerned with the other coop. Moving 3 juveniles and two bantams into someone else coop might be a bit more dicey. It will help that you are also moving 2 older birds with them, that do get along together? 7 birds going into a flock of 6 birds is going to help.
I think it can be done, and I would not expect a real wreck, but do watch the bantams and young birds of the second group.
Mrs K