merge local user to domain when connecting to active directory

We are moving from old Novell to Active Directory, and the procedure is usually that we first add the machine to Active Directory and let the users log on via Novell for some time.
After a while we remove the Novell client (via local admin) and assign group policies to the computer via AD.
On some machines when the users log in to the domain first time, they are presented with a brand new user account - all their old settings and mails are gone!
Is there a way to merge the local and domain user into one account?
I have red the article ID 21866532 - (Merging 2 user accounts) but it doesn't apply - too difficult. There must be a simple command somewhere.

Hope that someone can help here