Can I purchase another domain slot for my multi-domain certificate?

  Multi-domain certificates FAQ

In order to add more domains, you need to purchase additional slots before certificate activation or reissue. The purchase is done from your SSL list > click on the certificate ID > click on “Add more” button in the “Secures X of 100 domains” line:

You will be redirected to the shopping cart where you will see the option to pay for additional domains. Once done, you can reissue the certificate with the extended amount of SANs.

It is possible to change the domain names within your multi-domain certificate after it is issued via reissue. The following guide will shows the steps on how to add domains during reissue.