Just make the generic AI files work, and let the unmodded races fall back on that.
Be sure not to include the bitmaps in your mod, since they will cause massive unnessesary bloat. You don't want a download that is 1 meg worth of mod, and 20 megs worth of shipsets that people already have and that you may not have permission to redistribute.
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Se4 will look for any missing AI files and bitmaps in the generic and stock folders, so don't worry about missing files. Just be sure the generic race AI works
