Moving migrated emails in Gmail

G'day all

Can anyone advise whether or not it is possible to move imported emails inside Gmail to be nested directly under the destination inbox?

ie: I have imported a users email from Xtra, where they have been using it extensively for years and have created all the subfolders in the xtra web portal. (yes yuk I know). So now I have imported the whole lot into their Gmail, but I'm stuck as to how to now move said imported folder structure to be under the new inbox, rather than one level down under the xxx@xtra.co.nz sub folder (label).

I'm suspecting that the import is in fact only IMAP itself and so if /when we were to kill off the original xtra account, all the imported email will dissappear in a puff of smoke...?

Hope I've explained it clearly, thanks if anyone can..

cheers

frank