Multi-domain certificates can only be renewed with the same number of SANs (additional domains). There is no option to change the number of additional domains during checkout. However, there are two ways to add more additional domains to the renewal certificate: purchase additional domains before activating the renewal certificate; activate the renewal certificate and purchase ..
PositiveSSL & EssentialSSL Certificate renewal InstantSSL, PremiumSSL and EV SSL Certificate renewal Multi-Domain Certificate renewal Next steps SSL Certificate Renewal becomes available in your Account from 30 days before its expiration. We’ll send you email reminders 30, 15, 7, 3 and 1 day before your Certificate expires, so you’ll have plenty of opportunity to renew. ..