Sorry in advance if this has been posted already, I searched for a while and couldn't find anything quite like this on the forums or the wiki. A few years ago in my game a dwarven caravan came, and shortly after we were done trading some goblins sprung an ambush and popped a few of the traders and their animals. I actually kind of appreciated it at the time because it gave me a few precious steps to get all my dwarves inside. But for some reason, after the threat was gone the merchants wouldn't leave. After some looking around, I realized that one merchant seemed to be trapped behind the wagon of one of the dead ones, and none of the bodyguards seemed to want to leave without him. At first I tried getting rid of the wagon before recognizing that those things are damn near impossible to destroy. Then I decided just to give up on that caravan, relocate my depot, and seal the old one so they wouldn't cause problems once insanity set in.
It's been 2 years since, and I haven't gotten a dwarven merchants in either of them. I tried to dig a channel under the wagon, but it wouldn't fall through. Apparently they can fly... So I'm guessing the dwarves won't come back because they didn't ever leave, which also might explain my nonexistent immigration in the past few years. Is there a way to get them to leave/kill them? The only thing I can think of right now is to wait for the next set of goblins and shepherd them over to there, hopefully they'll finish the job this time.