Settings/Manage Unique Websites Format?

Example: A user has different usernames for

host1.example.com

host2.example.com

host3.example.com

etc.

Usually, doing a login to any one host, will show all usernames for all the above hosts in the drop down for username. It's random'ish if it selects the correct username, by default, for a specific host. By poking around, I discovered the setting, in the subject line, that helps with this. By entering each host name into that setting, it will only show usernames at login for a single host.

My question is this: Can something like *.example.com be entered to consider all hosts of example.com to be separate without me having to type each fully qualified host name into the setting.