There is one thing in the game I'm really fed up with: Whenever a conversation is started while more than one pc is active, it's usually not the party diplomat who is selected by the game to do the talking. I managed to edit the scripts so that the party leader is chosen as dialog triggerer, but that only works when I initiate the conversation. If the npc starts (by map trigger I guess), it seems the script is ignored and the game still randomly? selects which pc does the talking. Is there a way to either edit the map triggers or make it possible to swap the talking pc during dialog?
Yes it is possible, many npc's have already received this treatment, however a few have been missed, no specific effort has been made to uniformly eradicate this kind of issue as yet.
NPCs who initiate chatter via heartbeat should do this (with the usual checks for in range and not dead etc), yes.