well you will need to divide at least the males from the females at around 5 months of age or your pen will over flow with brother sister crosses . but yes they will establish a pack order and they will fight like hell sometimes in the process . but just remember some gyps will have their first heat cycle at 6 months .
Good info Mr. Whitten.
I personally have done the same thing you are doing, built a big pen that encloses my off the ground kennels, when I feel the pups are big enough to be on the ground and out of the kennel thats where they go, when they are between 5-6 months old I put them on a chain like the rest of the dogs. I have a gyp right now that will be multiplying any minute and I plan on doing the exact same thing, keeping all the pups to work.