How about someone takes the edu, and then under ownership for each unit just adds a commented out line. In that commented out line, a new ownership list would be contained (that works but is just commented out), but this new ownership is just those factions who would get the unit in custom battles. This could be a part of the official version of the edu file, and all one would have to do is go down the list and move the commenting out character to the line above instead of having it on the one below. that could be saved then as a different file. Both files could be shipped, and the player just swaps them out if they want a campaign or a custom battle MP match.