I think I found an bug in Virtualmin. As I could not insert an issue I will post it here.
Currently I have 2 top-level virtual servers configured. They have both a different valid wildcard SSL certificate. I created under both top-level servers, new sub-servers for hosting sub-domains.
With the first sub-server the SSL was taken from the parent top-level server and the 'Manage SSL Certificate' page gave me the message that the certificate is managed by its parent. Great! exactly the way I want it. When I created another sub-server under the other top-level server, it created an self-signed certificate and I could edit the certificate on the 'Manage SSL Certificate' page. That is not the way I want it!
To fix my problem, I edited the apache config files to match the same certificate, and I edited the virtualmin configuration files in /etc/webmin/virtual-server/domains/. I found the line 'ssl_same=xxxxxxxx' which was missing in the other sub-server config. After the adjustment the 'Manage SSL Certificate' page gave me the correct message!
So, when creating a new sub-server, the check for the same parent SSL is not quite correct. Can someone report this?
Thanks in advance!