Flocks of multiple ages don't play well together

We let our first set of chicks grow up in the same coop as our laying hens because I figured they'd pick up some foraging tricks from these matriarchs.  I quickly learned my lesson. 

For the first month or so, the chicks barely interacted with the adults.  They were fed in their gated off corner of the coop and were able to slip through holes in the pasture fence to forage wherever they wished --- which generally meant far away from those big, scary hens.  But when the time came to kick the first brood out of their protected corner so that our broody hen could raise brood three, trouble started.

The old girls were and are territorial of any food introduced into the pasture, so if I try to feed both flocks together, the hens chase the tweens away even after they've gorged and can't eat another bite.  I ended up having to feed the tweens in the supposedly resting pasture 4 because the smaller chickens can slide under the gate and get to this protected paddock while the old girls are left to cool their heels in pasture 3.

The main problem with this arrangement is that both pasture 3 and pasture 4 are now overgrazed, but I can't rotate or I'll have to find a new way to get the youngsters a bite to eat.  I'm a purist and am offended by even the slightest foul fowl smell --- I figure you're doing something wrong if you can see or smell chicken poop in your coop or pasture, and I can now do both.

The other problem is that the overcrowded coop no longer seems to be a conducive spot for laying.  I thought our old girls had just reached "menopause" until I found this stash of two dozen eggs hidden in the weeds.  I guess there's just too much activity in the coop to lay eggs.

I've solved the problem for broods 2 and 3 by the simple method of giving each young flock its own space --- half or all of a coop and a whole pasture apiece.  Two pastures per flock would be better so that I could rotate back and forth, but that might be pushing  our ability to get pastures built.  Luckily, we can divide each coop in half and have the equivalent of four coops at our command --- just the right amount of sections for a permanent flock and any number of broods since the broilers go in our bellies after three months and their space can be reused.