How would i make it so that when, in a group of say 20 npc that are fighting against another group of the same amount, if on npc acidentley hits another npc in the same group that the npc getting hit would not take damage and will not fight the friendly npc?

Not sure about not taking damage, but if you put all of the allied NPCs in the same http://cs.elderscrolls.com/constwiki/index.php/Category:Factions, set the disposition very high and check the "http://img97.imageshack.us/img97/7554/specialcombatflag.jpg" flag, that should prevent them from becoming hostile to each other.

Ah, Thanks.