Iv got a problem with my migration.

I need to get my forum/cms up and running in a temp directory and import the users , then give the moderators access so they can start writing articles.

It will sit like this for maybe a month or so, with the current production SMF forum that we ran the IMPEX against running away as normal.

Obviously after a month or so, there will be new users, new posts threads etc on the production site, so I would like to re-run the Impex script to basically update what was missed in the previous month or so.

Is this possible ? Will it create duplicates or junk data?

Whats my best approach for this.