You have ample space, that is good. Do look up clutter in the run. It really helps make use of the 3 dimension, the vertical space, and it lets birds get away from each other and out of sight of each other.
I agree, 2 cockerels is too much, says the lady that right now has 3 cockerels and a mature rooster. I am not saying it won't work, but a good rule of thumb is the more you have, the more trouble you get. They are in the darling phase, enjoy that. We all do, that is what I am doing right now too.
Make plans for the ugly stage. I will get my flock down to one rooster/cockerel by October. I have a plan. You need a plan, because it really can be ugly in what seems like a minute. Also, if you have children, they tend to attack children first. If they are under 6 years of age, be very, very careful. Kids can take an attack in the face.
As for your set up, I think I would open up the 8x8, I am taking that it is attached to the other pen? But I would do so, so that if I needed to make it back into two pens, I could. A handy thing to have.
I would let them all out to free range late in the afternoon, while I opened up the fence between them. They will naturally just come back to the coop/run, and I would expect them to sleep where they have been. You hens are not many weeks off of laying, and when they start laying, they will no longer be two flocks. It is kind of neat, but all of a sudden, the two flocks just merge.
At that time, I would expect some of them to go into the big girls coop. At that time I would close off the little coop and everyone will more than likely go in the big coop. Check near dark, and toss any stubborn one