zensyslog ip address assignment

Is there a way to assign multiple IP address to the zensyslog service? We have a private network used for management and we would like to have the syslog service listen on both the Public facing address and the mgmt address but when I click the assign button in the IP assignments section, I get a dialog box to change the IP but the drop down list only has 2 options, Automatic and the external address. Selecting automatic just sets the external address. Do we need to make the interface known someplace else in control center?

Thanks