On my Linux server running with the Plesk (Onyx, version 17) LetsEncrypt extension (version 2.5.0), I’ve successfully managed to add domain aliases to a certificate with the -d option on the command-line:
plesk bin extension --exec letsencrypt cli.php -d alias.domain.com -d domain.com
--webroot-path "/var/www/vhosts/domain.com/sites/domain.com"
I’m still waiting for the renewal date to see what will happen, but I’m wondering: when the certificate will be automatically renewed, will all alias domains be included again?