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.)

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disqus support told me the answer is no.