If you already have a Creator or Contributor in your database, RIMMF knows not to import it again, and links the imported entity record to the appropriate Agent. If RIMMF links to the wrong Agent, then remove the link and link (or import and link) to the correct Agent
If you know that you already have a Work or Expression in your database, do not import it
If not importing one or more related entities, you must go back and make the linkins manually (for now, until we can reliably dedup)