EDIT2: Solved! (see post below this one).
EDIT1: civ_unit addRating -10000 works, however, BLUFOR will kill the CIVILIANs as well. Since BLUFOR is around, this is not acceptable.
First post here, since I've found all other solutions myself before. So yes I used the search function.
What I want is fairly simple (I would think): OPFOR moves into a town (trigger), which suddenly makes them hostile to CIVILIANs. However, whatever code I put in the trigger action box does not work. Not setFriend, not joinSilent WEST, no nothing.
Initlines, init.sqs and mission.sqm work, I know that. But that doesn't let you change sides during gameplay.
(Background: I want a storyline of seemingly friendly troops getting in a town, acting all nice and friendly, then suddenly start killing people. Ok, kinda harsh, but... that could be life in a war torn country.)
Thanks in advance.