Webmin SSL certs -- different from dovecot, postfix

SYSTEM INFORMATION
OS type and version ubu20.04
Webmin version 2.001

I somehow got my configuration to use different certs/domains for webmin than dovecot/postfix/proftpd, which is what I want. But I don’t remember having to edit /etc/webmin/miniserv.conf manually to do it, or to actually mess with the certs themselves.

But it seems that the cert/ca/key files for webmin (as pointed to in miniserv.conf certfile=, extracas=, and keyfile=) are all in /etc/webmin, and they just expired.

So I tried manually editing(!) /etc/webmin/miniserv.conf to point to /home/domain/ssl.ca, etc, and restarted webmin, but it didn’t work – got actual binary noise in the miniserv.log and a bad SSL connection.

Was there some magic way that I managed to configure webmin (only) to use the certs from a domain other than pushing the “Set as Default Services Certificate” button in the SSL config of the domain I want to use (which would override the dovecot/postfix certs)? Or did I just imagine that I didn’t have to re-copy those certs over to /etc/webmin every three months when they expire?

No response?

How are the ssl files in /etc/webmin maintained?

When you push “Set as Default Services Certificate” or “Copy SSL Certificate to Services”, how does it ever know to renew the cert?