I posted an example of using a JSON to tweak a random NPC prior to spawning.
Also, a question about why changing FactionID in the JSON doesn’t seem to work.
Comments welcome (on the original thread, if convenient)
I don’t know my beamdog forum password right now so I have to write here.
If you compare the jsons before and after ChangeToStandardFaction() you’ll see that FactionID has changed from 1 to 2.
Setting FactionID to 2 right away would create a non-hostile NPC.
[edit]Just remembered the password so I’ve made the post at beamdog forum too 
[/edit]
The actual engine constants for the standard factions are 1 higher than the nwscript ones.
Engine:
STANDARD_FACTION_HOSTILE = 1;
STANDARD_FACTION_COMMONER = 2;
STANDARD_FACTION_MERCHANT = 3;
STANDARD_FACTION_DEFENDER = 4;
Nwscript:
STANDARD_FACTION_HOSTILE = 0;
STANDARD_FACTION_COMMONER = 1;
STANDARD_FACTION_MERCHANT = 2;
STANDARD_FACTION_DEFENDER = 3;
You’d use the engine constants for any gff related editing.
Who knew? 