- Back up module file
- Open module (don't open any areas or anything!)
- Open GFFEditor.exe and go File → Open. Go to your \My Documents\Neverwinter Nights\modules\temp0 folder and open the .are file you need. This is identified by the "ResRef" field in the Advanced Area Properties.
- Find the Tileset line entry which is a CResREf field type.
- Edit the value to be something new, eg: tts01 could become tts02 (Rural Winter upgraded to Rural Winter - Facelift). Click off the entry to enable saving (so the change is registered) and File → Save it.
- You now can open the area in the toolset and it should show the newer tileset:
- Save the module (if it doesn't have the save button active re-save a script or re-save a conversation file, don't open any areas)