Jesse -- I think my situation is similar to the original asker's. I have a standard SSL cert (paid) and I need to keep the existing domain on the cert and add one m. (for mobile) subdomain.  I'd  like to add the subdomain to the existing cert and not re-key. I want to avoid re-keying, because I can't afford to bring the site down. Is there any way to get this done? -- Val.