Enteruser is an extensible script for adding new users to a FreeBSD
system.  It can be used to enter a single user, and it can be invoked as
"queueuser" to add several users in batch.  Unlike adduser(8), enteruser
uses pw(8) and can be used concurrently by multiple admins and techs to
add users to a system.

Enteruser is also designed to be extensible.  Please see the linked
article for further background.