Messages/Jabber: Clean up messy Buddy Lists and start over

Basics

• Running Mac OS X Server 10.8.2
• Messages (Jabber) turned On
• We are not chatting with anyone outside our Jabber server

Problem

• Over time duplicate users have shown up on clients buddy lists
• Some users display as "Not authoirzed"
• Some client's Buddy Lists show old users that have since been removed

Questions

• How do I wiipe all Buddy Lists clean? (I am okay with deleting database and starting over if it doesn't affect anything outside of Messages)
• I have checked "Make group members Messages buddies" in the group that I want to auto-populate for everyone after I clear all the Buddy Lists. How do I make this happen after I clear everyone's Buddy Lists?

Any help would be greatly appreciated.

Thank you very much