Thx for kudos, Bucksnort. I am glad you enjoy my editor.
But back to your question - this "mod" works only in mission opened and saved in Mission editor. It would be enough if you just open WOFF campaign mission in Editor and then click Save button without need to edit anything. If you forget to open and save mission in Editor, mod is not being activated and you can meet MvR again.
However, this mod will eliminate any enemy ace shot down by you, regardless if the kill has been scored during edited mission or not. Editor reads your claim records before each mission, looking for any enemy ace and if found any, it cancels his assignment in the edited/saved mission.
I hope it is a little bit more legible now, although spoken with my poor (Czech)English.