[xwiki-users] subwiki ldap authentication

Hi all, I just recently upgraded to 5.3 and have now created a sub wiki for the first time. My main wiki is configured to authenticate using LDAP and has a base search DN set to an OU called "AllUsers". In Active Directory the AllUsers OU contains several sub OU's which separate users according to branch, department ect. Having the LDAP set up to search the AllUsers OU allows for anyone in our company to use the main wiki by logging in with their network credentials and works great. When I created the sub wiki, I went through the wizard and selected to only have local users be available in it, as this sub wiki is to be used and administrated by a specific department only. What I would like to achieve now is to have the users of the sub wiki be authenticated using a different search base than that of the main wiki (aka the OU that contains only users for that department). So instead of using the following, which is defined in the xwiki.cfg: xwiki.authentication.ldap.base_DN=OU=All Users,DC=mycompanyt,DC=com The sub wiki would use this for authentication: xwiki.authentication.ldap.base_DN=OU=Accounting,OU=myBranch,OU=All Users,DC=mycompanyt,DC=com I read in the documentation " Use cases of configuration to authenticate users with LDAP " that each wiki in a multiwiki environment can have its own LDAP configuration, however I am unable to determine how to do this, as there is only one xwiki.cfg file that contains my LDAP configuration and there is no mention of any LDAP settings in the xwiki.preferences page of the sub wiki. any help is greatly appreciated!