Bind / Secondary Zone - Primary IP Port

[dusty128]

Dear OPNSense community,
I have a primary OPNSense DNS server with bind, running on port 53530 with a zone.

Now I have a secondary OPNSense installation, where I want to put this zone as a secondary zone in Bind.

My problem is that I cannot specify the port in the GUI. I can do so directly in the configuration files, however, this is overwritten.

How can I specify the port for the primary DNS server on my secondary OPNSense Bind installation?

Best Regards,
Hermann