Report: IP last active, source other than dhcp

We have several subnets that use static addresses with "reserved" entries in MS DHCP.  When IPAM reports the Last Response date on the Manage Subnets and IP Addresses page, it always shows the current date since it saw the IP in DHCP.  However, people forget to remove unused address reservations from DHCP.  What I need to know is when was the address last *active*, ie seen in a scan or neighbor discovery.  How can I get a report where the Last Response does not include DHCP, just scan and neighbor discovery?

thanks

john

dis