Buddy list display not updating everyone

I use a distribution List to populate staff buddy lists server wide. (ZxChat: "Add all the members of a Distribution List to each other's buddy list") I recently made a change to everyone's "Display Name" but randomly staff have some that are not updating and some that did. To correct I had to
- Disable "Add all the members of a Distribution List to each other's buddy list"
- Delete the individual buddy from the user's list
- Enable "Add all the members of a Distribution List to each other's buddy list".

My guess is some users have their own special record for specific buddies. I'm wondering if there is a way to purge the entire IM database so I can control everything from my distribution list.

Thanks
Rois