Exactly that is the question. During data migration over several maschines since 2005 I have a lost the original module, but I still have the save game.
Resolved it myself. Pack the sav-file in the module folder, rename it *.mod and fire up the toolset. All these things I knew 15 years ago… 
Amazing! Never thought that this could work. My fist idea was to export all the stuff into a new module.
You can use the NWN-hak-utility after renaming the file to *.hak.or *.erf