LDAP shared rosters - different rosters for different domains

Hi, I'm setting up an ejabberd server for my company which will host like 50 different domains who are always adding and subtracting users. What we'd like to do is have shared rosters where the technicians can see all of the users for all of the domains, and but the users can only see people logged in on their domain, (and the techs) pulling the info from the LDAP server. Is this possible? Do I have to put them all on the same domain so that the techs can see them? Can one domain see another domain's users?