Hi Yvonne,
I think you've gotten this answered in other places already , but for the benefit of others…
Deployment Manager does not have the ability to add additional metadata after the fact.
The new Migration Suite for SharePoint (or the associated targeted products – File Migrator, Public Folder Migrator, etc.) has the ability to "Tag" existing SharePoint content. This allows you to update metadata on items that already exist.
Best,
Tim