[Suhiir]

If you're working on a campaign instead of a single stand-alone scenario one thing I've found useful is to create a "Base Scenario" using a blank map and buying/modifying all the units your campaign will use.

Then as you create each actual campaign scenario you can just load that "Base Scenario" into the editor and either set any units the particular scenario doesn't use to reinforce on turn 49 (presuming your scenario is shorter then that) or delete them (not as good if you want to keep campaign integrity).

This way you need only mess with the whole formation/unit alteration process once, and don't need to muck with the OOB.