Well, I'm back.
Don't forget, if you want a post to stay at the top, you can always mark it as sticky. Have a good time in Italy.
I didn't handle this well... my logic was that I didn't want to just append on the bottom of the topic because then people had to scroll through the previous (now irrelevent) absences to get to it. So I just edited the first post and deleted the others. But then I wanted it to be marked as 'unread' (not just pushed to the top of the forum) so I added a dummy post.
Obviously I should have just started a new thread with a single message, which is what I'll do next time.