how to add subdomains to non-main domains?

Hi,
I'm new to CWP doing my first installation and configuration. The server will only be for myself, no other users / customers / admins.

So I have created a single user account and configured it with my main domain. Then I have added several other domains to that same user.

When I go to Add Subdomain the domain drop-down list only contains the main domain from that user. Is it not possible to add subdomains to non-main domains? Do I have to create a user per domain to be able to add subdomains to all of my domains? Or am I missing something? ;-)

Chris

OK, nevermind... I have just added a user per domain as a workaround. Though it would have been easier to manage if only one user was required for all domains.