Migration Manager for Active Directory

Can you only migrate computer objects to target for source with existing user/group accounts in the target

We were recently acquired by another company in which we need to move our resources "ONLY" to the new “target” domain.  Currently, ALL our users already have accounts in the target domain that were NOT migrated via Quest MMAD.  We want to see if it’s possible to move all workstations and servers to this new “target” domain WITHOUT a trust and map their current “source” user account to their “target” accounts so the resource manager can do the rest.  Basically, we need to migrate all computer objects to a new domain where the users were NOT migrated over but manually created prior:

Source UN format:   steve.smith

Target UN format:   smiths


Thanks and welcome any feedback or suggestions.