LABE - LDAP Address Book Editor

Hi,
I'm working on putting up a solution based on LDAP for several puroposes.
One of the goals is to build up a shared Address Book.
Let's say some users within the directory want to query the ldap users branch with their client address books to gather contact informations..i think this would be easily achievable.
But i have the problem of let people share not only contacts, but even *groups* of contacts - from the branch "users" of the DIT, let's say - to do some mailing-list oriented stuff.
How can i set up my LDAP directory ( using OpenLDAP Vers. 3 ) to achieve that?
Is your web tool capable of doing that? In case of a positive answer it would be a crucial tool for me.
Thanks in advance,
Cheers!