I like using FOOK2, but I also like the vanilla R91 as the main assault rifle. Now I would like to put the R91 back into the place that the HK G3A3 took from it. How do I do this? Please and thank you.

Whoa! That's the second time I've read about that today. O_O Weapons aren't really my department and that call wasn't mine, but it might be possible to just attach a script to the replacement which would add a vanilla assault rifle in any given replacement's stead, then delete/remove said replacement. *tinkers*