How to align a user account (< 9 characters long) to a specific AD domain?

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How can I align a user John.Doe to one AD Domain, and user Jane.Doe to another AD Domain in the same forest?

Have tried using the winbind separator ex: domain1+jdoe, but long Domain names and long user names get messy.

Authenticating from with previously setup UID and GID is the challenge.
Dont want auto-created accounts.... just the password authentication to non-cached (if possible).

In short, can I map:
jdoe1 to
jdoe2 to

Ideally, one would login as jdoe1, but it might also be acceptable to login with the UPN (, provided that the short name (jdoe1) would appear in system output like 'ps -ef ".

Thanks for your thoughts.