Ok this is a bit of a hard scenario.
We are in the middle of a domain migration, we aren't doing it all at once which means gradually we will move users over at a time. This means that we need to be able to have the users permissions for the company shared drive mirror their new account.
Currently the company shared drive is located on the old domain.
Example: Auser is in Olddomain. Auser is able to access different folders/files in Oldcompanyshare.
Auser will now migrate over to Newdomain. Auser gets a new username for Newdomain which is NAuser. NAuser needs to have the same folder permissions that Auser has to view files within Oldcompanyshare which is part of Olddomain.
Please help, otherwise I NAuser will need to be given permissions manually which is a major time killer.
Fileshare is Windows Server 2012 R2 based.