When I am working with someone via FogBugz, I typically separate their requests by case and communicate via email.
The problem is that they don't follow that same organization and I'll usually get replies from the LAST email I sent them that pertains to a separate case. Is there a way to move that email (BugEvent) to the correct case, without having to get your hands dirty with the DB?
What I usually do in this type of situation is to forward the message from the wrong case to the right one. e.g. something for case 123 was sent to case 456, so I hit forward on it, select "correspondent" in the From drop-down, put the fogbugz email address in the To field and change the case number in the subject from 456 to 123. Sadly I can't remove that email from case 456, so I just add an edit that says what I did.