multiple xymon server IP

Built a new xymon server to replace an older box.   We have a DMZ.  To avoid doing the paperwork to create new firewall rules I was hoping there was a way
to "multi home" the new box so that, once the current one is retired, it can assume that IP be happy, from a xymon perspective.   

Simply changing the new server to a single (old box) IP is not feasible for reasons I cannot get into.

Thanks for any pointers.