"introduce them properly" as in use the acclimation and introduction process I listed above. 
Here, I'll just put a step-by-step for what you should do. 
1: get rid of 3 of those males. Eat them, give them away, whatever, as long as it's humane. While you're waiting to get more, keep an eye on your current ones. Make sure your male isn't over-mating the female. You may have to separate them if he is.
2: get adult females, if at all possible. If you can't, hatch them, or raise them from baby chicks, and get them to being fully feathered before you try to put them together. 
3: put the new quail in something that they can see through, and set that container inside your current quail enclosure. Watch how they interact through the container with the old quail. If you don't see any aggression, go to step 4. If you see aggression, go to step 5. 
4: put the new quail inside the enclosure with the old quail, and watch. If they chase each other and act aggressive for more than a few hours, go to step 5. If not, you're done. 
5 (for if they don't get along): separate them. Put the old quail and the new quail in separate enclosures, where they can see each other but can't touch each other. Wait a week or so, or until they stop being aggressive at each other through the wall. 
6: repeat step 4.