Check for Certificate AND Username

Hi, I am using freeradius to secure my WLAN. Everything works fine so far. But i`m not much of an expert. What I have now is a working setup using EAP/TLS and self-created certificates. But how can i achieve the following: - Client sends certificate and Username/Password (done) - freeradius checks for valid certificate (done) - freeradius ADDITIONALLY checks Username/Password with another Radius-Server. I guess I have to use the proxy settings. But how do i make freeradius check BOTH conditions? Any help would be appreciated Regards, Wolfgang Burger