rename address book entry (10.5.8)

Good morning.

I am transferring email address book contents from a very old email program to MAIL (3.6) for my G4 PowerBook.

For many of the address book entries, I have a "nickname" that is linked to the actual email address and formal user name.

How can I enter these "nicknames" into the MAIL address book and then have the "nicknames" appear in alphabetical order?

Thanks for your time.