Since the party will be getting into Denerim BEFORE they meet Az: Azabeth Kordura is currently wanted for the death of the Arlessa, and has a substantial bounty on her head. Any of her contacts in the poorer areas of the city could tell you that she's been run out of town and hasn't been heard from in weeks. Someone with l33t information gathering skillz might dig up Black Matthew himself as an NPC contact. (Undecided on that one, I love Matt but he would need a PB. XD)
This is especially important information for Lalin, Conlan and Dolain, because Lelahai will be plastering her sister's picture EVERYWHERE in an attempt to hunt her down, and the information will be pretty hard to miss.