If you are an odd's girl or guy, then 90% it won't work. You do have space, which did increase the odds slimly. That many roosters is too many roosters for the few immature pullets that you have, even if you get down to 2 roosters. That is the reality of roosters. 
You have a very immature flock, which is going to be a lot of hormones running around, especially if you are in the northern hemisphere and spring is coming. Cockerels can really make pullets lives miserable. The more you have, the more aggressive and competitive they get, leading to multiple breedings to one pullet, and fighting amongst themselves.
The old boy is not going to like any of the new boys. Especially if he has fought before. He is going to be pretty determined to get his licks in early. The aggressivieness of Margarette does not bode well for this.
You can try it how you want, but do have a plan B, C, and D set up and ready to go. They are your birds, give it a try. But truthfully, I would expect this to be a pretty miserable flock, and stress leads to poor health, and less eggs, and sometimes loss of life.
One really can't keep everything. I know you came here wanting non culling solutions.  I fully planned on giving advice as to clutter in the run, escapes and hideouts, extra roosts, feed stations, and water. Those things can really help. But you have too many roosters. I too, would recommend only keeping one, and it might be best not to have any. One should work, you have the space.
Mrs K