Tiwaz- It is a narrative reason. They came across an injured elf who with his dying plea asked them to prevent the ogres from obtaining the Heart of the Irda. Your idea of an NPC prompt to get them back on track of the main quest would work well if I need it. One of the players is a disguised Irda with a pearl earring that allows her to send messages to her mentor. Its supposed to be a one way system of communication, but the player hasn't been remembering to send messages to her mentor, so maybe making it able to send and receive messages, maybe when Solinari is full, is an idea.
Weldon- Speaking of the PoC, my original idea was to take the KoD, SoS and PoC and tweak them to fit in with my campaign. Obviously that'd take quite a bit of work, but I really would like to run a group through those modules and I have no plans to ever have Chaos appear or have an Age of Mortals etc. so to run them will require a lot of work. Also, I *loved* the original Wing Commander.