I think you could several pairs or fish but the most important factor in keeping them together happily without quarrel would be to purchase them all from the same dealer/shop, all at the same time/day as really young juveniles and let them mature in your tank. Try to get ones that are already together in the same tank in the shop!
At this age they will ALL be males (all clownfish start life off as males!), but as they get older they will form a sort of heirachy in which the most dominant male will grow larger than the rest and turn into a female, then the second most dominant male will become the first most dominant and pair off with the female, the rest will all go down in their order eg. 3rd, forth, fifth dominant etc etc. If ever the female was to be removed or died, then the dominant male would eventually turn into a female and the second dominant male would move up to most dominant and the rest would also move up a 'rank'!
With this method even though all your clownfish will be purchased small and nowhere near fill your tank, they will eventually mature and most problems would stay at a minimum, as buying mature adult clownfish could/would cause potential conflict amongest them and you will always find that the more dominant ones will harrass and even kill weaker competitors whilst defending territory!
But once established in the tank, it would not be recommended to add any other clownfish as the 'new' fish would get harrassed even to the point of death!
Make sure however, you do provide adequate hiding spaces/corals/anemones for any fish that may get picked on or bullied by other clownfish as they try to fight to move up ther rank in the heirachy!
Hope this has helped! Good luck with it all!
