How do you get the sidequest involving Nalia's Father's Funeral (and the kidnapping quest)? I took care of the troll problem a long time ago (without Nalia's help). Now, I'd like to involve myself in this quest.

You have to have Nalia in your party for the quest to come about, and two weeks (game time I think) needs to have past since you cleared the keep. You'll be approached by a messenger.