How can a new domain pair be added to an existing job?
In order to add another domain pair to existing project start QMM (Quest Migration Manager), right-click on Directory Migration node and select "New Source and Target Domain pair" and then follow the wizard.
One project can have multiple domain pairs, same domains can participate in multiple migrations but you cannot create a second domain pair where source and target domain would be the same as in first domain pair, the error will inform "A domain pair with the specified source and target domains already exists". Most common scenario during the migration is when different source domains migrate to the same target domain.
QMM User Guide has a section called "Creating a Domain Pair", when creating a second or third domain pair steps would be the same as when creating the first pair. It is advisable to use different matching attributes for each domain pair, for more information please see Quest KB article 14420: https://support.quest.com/SUPPORT/index?page=solution&id=SOL14420