What should be an incredibly simple task is confusing as heck.

I have someadmin@domain.com who manages a bunch of domain names.
I want to add thenewdomain.com to zimbra and have someadmin@domain.com manage the domain name.

You would think there's some way to list/add/edit a bunch of domain names to one administrator but if there is - it's very well hidden. Does anyone know how this is done?