Adding new missions/campaigns

Hello.
When I add new campaigns, missions etc etc, I always have to override earlier waw.files for sounds from other campaigns/missions, is this correct way to do it. Or is there better way, where I could actually have original waw.files in my different campaigns/missions?
Thanks!

PS. I want to have my all different campaigns/missions to be played anytime I want, so different folders for each campaign/mission , from where I make them active, one by one, aint gonna work for me.