It is recommended that domain names not change frequently. Changing domain names requires the reinstallation of every server that belongs to the domain whose name has been changed. For clarity, domain names should be reflective of the general business areas they serve.
For the XYZ Corporation, a global group will be defined for every Resource Domain that includes all of the users who use that domain as their primary resource base. For both models, global groups will be created for all departments/locations and the members of each department will automatically be made members of their department groups. The group name should be reflective of the domain and the department (XYZ-UK). Other groups may be created for job categories (XYZ-UK-MANAGERS).
Ideally one user ID/password would allow access to all of a user's resources. If you want to take advantage of Microsoft's Client Services for NetWare®, in which the Windows NT username and password is passed through to NetWare, then set up the user account on NetWare with the same account name and password as in Windows NT. If there is no capability to send the user's password to other systems (such as Banyan® Vines®, or some databases), the next best thing is to at least have a consistent full name property within each company organization.