How To Add custom subdomain to letsencrypt issued certificate

I installed letsencrypt from the cwp panel.

I need to add a custom subdomain to the letsencrypt certificate. How do I edit the letsencrypt certificate?

I see from the letsencrypt website I can "expand" the certificate.

Can I reissue the certificate from the command line?

Does cwp process letsencrypt certificate any special way or could I process the certificates from the command line without messing up the letsencrypt app?

https://github.com/certbot/certbot/issues/2230

For anyone who has this issue, I found the solution

https://www.valife.co/2016/03/wordpress-multisite-lets-encrypt-ssl/

Add a new subdomain in cwp and then run letsencrypt on the subdomain.

That will register your subdomain with letsencrypt and secure your wordpress multisite subdomain