So, I have made dozens of factions successfully with ORBAT tool, really love it and have got it down without a problem now. The only issue I've run into is how to edit my factions after I've already created them, packed them into a PBO, etc.
For example, if I want to go back and add additional units or groups, when I load up the game go into ORBAT tool, find my faction in the list > Edit and make changes and export it, overwrite and repack the PBO it errors out on trying to load the game. The only thing I can ever end up doing, is create a whole new faction from scratch and just replace the original. There has to be a better way of simply editing one of my existing factions right? It seems like when I do this though, it wants me to have an ADDITIONAL PBO for the edit, on top of the original pbo for the faction.