How if i wanna add more Piwik_CountryList in Countries.php

In order to set the default location_ip for desired country. I would like to know how to add more $GLOBALS[‘Piwik_CountryList’] to the list in core/DataFiles/Countries.php so i can change them in the core/Common.php to specific country easily and not point the “unknown” IP address to “United States”. Thanks.