Please help. Need to move topics by usergroup to diff forum

[CSSlife]

I've got myself into a dilemna :S

I had an RSS scraper bot on Xenforo which scraped reddit and instead of assigning posts to a user it essentially posted them as if they were posted by the reddit user that posted them (ie. /u/reddituser)

When I converted over to IPB all the topics now show as being posted  by 'Guest /u/reddituser'

Well stupidly I was merging some sub-forums into its parent forum and I inadvertently managed to moved all the topics from this RSS Scraper forum into the main forum merging genuine posts with scraped threads by all these Guest posters.

Initially I thought okay, no problem... I'll just move all posts from the members usergroup into a different forum and that'll separate everything but I found there's no option to copy all topics by usergroup, only username or date etc...

Is there something I can do to fix this mess? Please say there is :S Any help whatsoever would be greatly appreciated!