One thing that might be worth trying, and it doesn't need Joe to do it. When there are threads which seem to be duplicating each other, when we want to reply to a post we can write the reply on the other thread, and stick a link to it on the superfluous one.

It'll take a bit longer, because it's necessary to write it so that what we say makes sense to someone who hasn't read the thread and the post to which we are responding; and there's the mechanicas of putting the link in as well, though that doesn't take long. But taking longer over a post isn't a bad thing anyway