Using multiple Active Directory / LDAP branches

Hi

I've set up RTC to use AD, but the node we're using is effectively a 'leaf' at the bottom of a branch. I now have the requirement to include other 'leaves' at the end of separate branches, is there a convenient way to do this. I'm guessing that the options are:

Is it a case of pointing the Base Group DN & Base User DN further up the branch, giving potential access to all nodes further down the branch, or can you specify specific AD areas you want to use?

Thanks
Alan