I'm new to the list and is the first time I use webmin.

Maybe the answer to my question is in the official documentation but, sorry, I can not find it.
I had created a webmin user which only has access to the webmin module "System-> Users and groups".
This user must create and manage some linux users (these are the users of some client connected via LAN to my ltsp server were run webmin).
I would not like that he can see or handle unix users like cups, lp etc..
I would like
that he can see and manage only those in the "users" group.
My version of webmin (on ubuntu) is 1.510.
Thanks for any suggestions