Pfsense haproxy and acme

Hello everyone, I’m writing in fact I’m paste a post for which I haven’t had any answers yet. I ask if anyone can help me on how to do it.
I tried to get an acme certificate for my pfsense firewall with the acme duckdns procedure. The process was successful and the certificate is valid. Having on the pfsense two other free duckdns host names registered via the pfsense dynamic dns service, I would like to use these names with haproxy . My doubt is how to do it in concrete fact. Having created the account key on the pfsense, in the certificates menu I find the one in production that works regularly. To add these two names , just run add certificate after the existing one ? If yes, I just have to repeat the same certificate request procedure but with the variant of the name that interests me (one of the two names that I should configure in haproxy) and re-enter the key with the url that generated me ducdns?
Also got these certificates how do I select it for a specific server that is part of a backend? Another question is to run a server in lan that has its LE certificate and therefore when configured on haproxy on pfsense, as soon as from the internet I query the fdqn name of this server, it is solved by the firewall and passed to HA, but the default pfsense certificate intervenes, always valid for the pfsense host but not for the destination.

Thank you .