Hmmm. Well, if you want a good all-in-one scenario, what do you think of Kunsel getting a little more proactive in looking for Zack during those years after Nibelheim? Picking up on a bit of gossip here, looking into a classified file there, digging for any information he can get on Nibelheim as Zack's last known location... I bet it wouldn't even be hard to find a mission in the area that would give him a chance to check things out himself.

Need a buddy to fish you out of that pickling tank there, Zack?

If you have another idea, though, I'm all ears!