How to add new DHCP IP address scope into SEP client Location Specific policies

People,

I'm about to commission new floor in the office with the new IP address scheme / class, how can I add the IP address class so that the Firewall still accept it as the Secure Internal Network in the Location specific policies ?

I'm using SEPM 12.1.3 and SEP client ranging from 11.0.6 into 12.1.3

Thanks