System->Administration->Users and Group tool "mismatch" with adduser tool?

[Daniel B. Thurman]

Being an "old fart", I am used to adding users
with the old adduser tool and I noticed that in
doing so, using the System->Administrator->User and Groups
tool does not even "see" the newly added users & groups.

So, how does one go about forcing this Gui tool into seeing
what is in the /etc/passwd,group & shadow files?

Thanks!
Dan