Mass-modifying Key bindings

I'm trying to modify a series of vehicle specific key bindings en masse and struggling. Previously I had managed to make the changes I needed on one vehicle, then copied the resultant .DIFF file into the inputmaps folder in the my documents BeamNG folder for each vehicle. This doesn't seem to be working now for some reason? Have I done something wrong or is there a new way to do this? I want the exact same controls for all vehicles, but there are nearly 30 bindings I need to make, so I'm loathed to do it for all vehicles one by one. Any help would be appreciated.