I love your coop, BTW.This is how I do it. Littles have their own little run where bigs can see them for about a week. Then I open the littles run door and split the bigs run in half with temporary divider (at that stage in pic.) The wire where the red arrow is, is bent up just enough that a little can get in and out but a big cannot. There is plenty of clutter on the bigs side incase a little is getting chased and can't make it back to the "little's only" space. Also, the bigs run door is open to 5 acres for free ranging. I do that because they are much less interested in the little's when they are pre-occupied with foraging out there.
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