Sadly, it's not. At least, not in this case. For example: My quest is to 'report to Count Raichs, the Marshall'. However, when I go to the besieged town and enter the camp, the camp commander is Count Tribidan. All I can do is talk to him, enter the seige, or leave. If I enter the seige, I have seen Count Raichs, but I can't talk to him during the battle.