When trying to delegate modules to users in Webmin we are sadly limited by the ability to add users to only one Webmin group at a time. Fortunately, one can cascade groups in order to work around this limitation. Groups can function as a superset of one another as per the following example:
I require Alice, Bob and Cassandra to be able to alter SpamAssassin’s configuration. I can create a Webmin group called SpamAssassin_Users with access to that module and add all three users to it. Should I require Bob and Cassandra to additionally have access to the System Logs module, I can create a second group called System_Logs_Users with access to that module. I can make System_Logs_Users a member of the SpamAssassin_Users group and then make both Bob and Cassandra a member of System_Logs_Users. Bob and Cassandra now have access to both SpamAssassin and System Logs whilst Alice is limited to being able to Manage SpamAsassin.
Thus simple kludge can save you a lot of time when you finally sit down to delegate modules, but if you use this trick pay close attention to group permission inheritance!