No. To be able to apply the free SSL certificate, your site(s) need to use the Umbrella Host nameservers.
This is because the SSL certificates are installed locally to the Umbrella Host platform.
As we use the Let’s Encrypt free SSL service to provide our SSLs and they require that the authoritative nameservers are set to our own for our system to be able to issue Wildcard Certificates under the ACME DNS verification method - That is not something we control.
