The web-pages are recognized by their hash, so you can't change them after you setup the page. The problem is that you would have to supply HN with the link to the page, and then go back and edit the page to include the link to the new HN article. Since you can't go back and edit the page, you can't include the link.
the hash is a hash of the content itself, so the link is immutable - if you changed the content the link wouldn't be pointing to the same thing anymore.
