Interesting that you bring that up. Indeed, I too was thinking of it as an example of posting a series of articles as replies to an umbrella node. However, your characterization that those replies update their parent is not quite accurate. It could be done, of course; but my dacha (which I've restyled my "treehouse") is not an example of that.

OTOH, an example I've done of using a reply to update a root node, rather than modify the root, is Tk Photo Slideshow - Production Release.