[SR-Users] How S-CSCF route SIP INVITEs as per iFC ?

I have added an Application Server in iFC and try to route one user to that Application server for testing But INVITE to that subscriber following the default iFC. I am using ng-voice HSS Server. I have been trying to differentiate between iFCs for two different subscribers and unable to find the store location of SAA xml on S-CSCF and I am Unable to find xml file of required subscribers in wireshark traces as well because it says in SAR that USER_DATA_ALREADY_EXISTS and SAA didn't contain any XML file for that specific users. Furthermore if you can describe SIP INVITEs routing mechanism of S-CSCF, on which params or SIP Headers S-CSCF route INVITEs to Application Servers according to iFC ? Regards Hamid R. Hashmi