Work on multi-level maps separately

[benjcallaghan]

I am trying to map a raid zone that has multiple levels in it. Because it is a current expansion dungeon, it is difficult for me to access a cleared version. I have nearly finished /loc collection for the first floor, and I have started /loc collection on the second floor. I want to begin line cleanup on the first floor and adding extra geometry like stairs, but I'm afraid if I add new lines to the first floor, or to any other floor, Mapper2 will overwrite all of the changes I've made. Do I need to finish /loc collection for the entire dungeon before I move on to the next step?