New introductions usually go best if you put the new ones in an area where they can be seen but not touched for a few days. Then when yours start warming up to them you can let them loose. Expect a little pushing and shoving...they have to work it out. Intervene if it looks like one is about to...
Well, I don't like it either but once you see the damage over breeding can do you'll understand. They can lose eyeballs, be drowned by gang rape, get infections where their feathers are ripped out on the backs of their head and neck area. It isn't pretty.
Same goes if your drakes turn on each...
Drake flocks don't always work out well either. Many times they will turn their sexual aggressions on each other and it can end with injuries and even death.
My advice is to get rid of 6 drakes.
Your going to have issues. You will likely have to keep them seperate permanatly. Yes, they have a breeding season when it is the worst but they mate year round and 2 girls will not fare well with 7 drakes.