Adding another domain onto a pre-existing cert for another domain
If I already have 2 LE-certed domains (both, properly, on the same cert; which were certified at the same time) and I want to add a third, different domain on that same cert later on; how should that be done?
I know I need a new CSR file, with all three domains. (right?)
Do I just run LE64 with ALL three domains to get the new cert?
I would think not, because I can’t get a new cert for the old domains before the renewal period comes up.
All 3 domains are highly related, so it’s preferred that they all be under the same cert.