how can we add new fields to proxy logs

Hi, Currently i'm using SplunkAppForBlueCoatProxySG app which is working as expected. My user wanted to add few more additional fields for proxy logs. We tested by adding only one new field at the END and its failing to extract existing fields in splunk. Anyone have any suggestions how to add new fields for proxy logs. Thanks in advance. @SplunkAppForBlueCoatProxySG