domain name alias and certification

hello -

is it possible to certify a domain alias name? i have a domain with multiple aliases (multiuser Wordpress).

or is a possible workaround to create a sub-domain virtual-server for each alias domain name, and then create a symbolic link back to the main domain name?

the main domain was certified without any problems, but the alias names are not answering with “https://” 443.

thank you very much.