How to connect local account to domain account?

Join them to the domain

Login with their domain credentials, logout

Login as local administrator (not the old account, not the new one, a 3rd local admin)

Right click My Computer and select properties

Select advanced system settings

Go to the Advanced tab

Click settings under user profiles

Select their old profile you want and click Copy to

Browse to the location of their new profile and overwrite it

If the Copy button is grayed out then reboot and repeat steps two to nine.