I ran another game with my nephews, but their friends' weren't there. Trying to get them to roleplay, I still wanted them to only play one character each, so in the quest to capture Ulag, I introduced an NPC that accompanied them on the quest: The Imperial Noble who funded the reward (since Prince Magnus has so little money), Richter Von Duffenschmirtz. This turned out to be a blast and kept the kids roleplaying all the way through the dungeon, since I played him up as the biggest most pompous person you could ever imagine who constantly remarked to them through the dungeon about just how awesome he was.
I made a few small changes to the quest besides adding an NPC. I added a room off to a side with an Orc Shaman. I changed a few goblins for goblin spearmen and a fanatic. I also changed the Chaos Warrior in the room with a Squig Hound. What self-respecting Orc Warboss wouldn't have a pet Squig to eat the warriors?
As the PC's struggled to fight the goblins and Ulag, Richter fought an epic battle against the Squig Hound. They finally defeated the Orcs and dragged Ulag back to town as a prisoner, but by the time the heroes finished shopping with their reward money, they were hearing talk all over the town that Richter and a few henchmen brought Ulag to justice and that Richter single-handedly faced the biggest most nastiest Squig Hound you ever saw while the henchmen (the PCs) cowered.