How to replace / renew a certificate ?

We are in the process on testing fortiweb to eventually deploy a vm-based solution.

For now, I have something working, and I am able to pass trafic trough the fortiweb (reverse proxy mode) to access the webserver I am user for now.

I was able to add certificate, and use SNI to access different websites on that server.

So, when a certificate is about to expire or need to be replace, I cannot import the new certificate, nor the certificate/key pair. I get an error that it exists and need to delete first. I cannot delete a given certificat since it's used in an SNI list.

So how are-we suppose to replace existing certs that are being used ? If do it by hand, best case it'll take like 30 seconds. During that time, clients would get another cert or an error. That's not verry acceptable.

I could always use the API to do it quickly in a second or so. But I would need to delete that cert from the SNI policy, and I haven't figured how, then delete the cert, re-upload the new cert, and then re-add the cert to the SNI policy.

Speaking of wich, is there a more detailed documentation of the API, as for what is the syntax to be used for each call ? I only found a quick reference basicly listing the possible calls.