Member Rara Avis
I must be missing something here? If you want a revision to be in the same thread, just use the "Post Reply" button and add it.
While I can see the advantage of displaying the two versions side-by-side, I would think the disadvantages would be far greater. When you start changing the order of the discussion, by inserting new content above old comments, things can get very confusing very quickly. Which critique is addressing which poem again? Anything added to correct that confusion would be at the cost of simplicity. Linear works pretty well.
On the other hand, if you add your revision to the end of the thread, and still want to see the poems side-by-side, it's as simple as opening a new window.
I completely agree that we need more "tools" to make critiquing easier and more comprehensive. I just don't think this would be one of them.