Had this in another system I was using before stepping over to EasyDiscuss. Basically an admin feature that lets you turn a reply into a comment. On my site the replies are reserved for proper answers to the original question, but many times people would unwittingly use it to discuss other answers making the post sometimes very cluttered.
As an admin, you would click on the "turn this into a comment" button and a popup would ask you which other reply this comment will belong to. Press OK and voila. Had to use it countless times, and hope this will make it into EZD sometime.
Alex