Admin External Users

I am trying to set up an address book of email addresses for all of my users to access. I do not want to share an address book but want the addresses in the global address book. I followed the documentation ( to define an external domain and post office to do this. However, I would like one or more of my users to be able to manage this address book (i.e., post office of external users). the control panel only lets me assign admins for the domain and post office of GroupWise users not the external user post office. is there a way to do this?