can disqus_identifier be added on page that already has comment?

i have a site using disqus comment system. I'm using their generic js code (as opposed to blogger, wordpress, etc)

in the js code, i didn't assign a disqus_identifier for any of my pages. But if i add now to a page that already has comment, will the id be associated with the page ?

i'd like to add the disqus_identifier because i may move the url or domain in t开发者_JS百科he near future.

(this is disqus specific question, not sure if this is best place to post or some other stacknetwork. Yes i've googled and read disqus faq.)

disqus support told me the answer is no.