FAILED TO COMPLY WITH CLRNC ON A PRACTICE BACKCOURSE APCH AND PROCEED DIRECT OUT THE BACKCOURSE VERSUS A LEFT TURN ON THE MAP.

Narrative

NW DME ARC TO LOC BACK COURSE RWY 3 AT ROW; TO BE FOLLOWED BY ILS RWY 21; AT MAP; PLT INITIATED CLB AND WAS HANDED OFF TO DEP. I DECIDED TO ASSIST WITH RADIO SINCE PLT WAS BUSY WITH CLEAN UP; SINCE I WAS UNFAMILIAR WITH MIXER PANEL; IT TOOK TOO LONG TO MAKE THE CHANGE; WHILE I WORKED RADIO; PLT INITIATED A L TURN RATHER THAN STRAIGHT TO TOPAN NDB; WHEN WE CAME UP ON DEP; THEY REQUESTED IMMEDIATE R TURN TO AVOID TFC CONFLICT AND THEN STERNLY REMINDED US THAT WE HAD BEEN CLRED TO TOPAN AND SHOULD NOT BE FLYING THE PUBLISHED MISSED APCH. PIC AUTHORITY NOT CLRLY DELINEATED. INSTRUMENT STUDENT ON LONG X-COUNTRY (RECEIVING DUEL FROM WIFE CFII WHO WAS SITTING IN BACKSEAT OF THEIR MLG) WAS RECEIVING INFORMED DUAL FROM ME (CFI) SITTING IN FRONT SEAT. WIFE'S NAME WAS USED ON FLT PLAN. (TOO MANY PEOPLE 'IN CHARGE' NO ONE EXERCISING AUTHORITY). CHANGE IN MISSED APCH PROC NOT READ BACK AND NOT UNDERSTOOD BY PLT (IT WAS OBVIOUS TO ME THAT THE DEFINED CLRNC WAS APPROPRIATE; BUT PLT WAS NOT THINKING AS FAR AHEAD AS I THOUGHT). POTENTIAL FOR TFC CONFLICT WAS NOT MENTIONED BY APCH ON TWR AND I DID NOT KNOW THAT THERE WAS OTHER TFC. IF I HAD KNOWN; I WOULD HAVE TAKEN CONTROL RATHER THAN USING THE MISTAKE AS A LESSON. I WAS IN THE PROCESS OF EXPLAINING THE MISTAKE WHEN DEP ISSUED THE CONFLICT WARNING. MY INEXPERIENCE PLAYED A ROLE HERE. NEXT TIME; I WILL ISSUE IMMEDIATE ORDERS OR TAKE CONTROL AND EXPLAIN LATER. MY HESITATION WAS ALSO INFLUENCED BY BEING IN AN INFORMAL POS IN A AIRPLANE OWNED BY THE PLT AND HIS CFII WIFE. I SHOULD HAVE ASSUMED PIC RESPONSIBILITY OR REFUSED THE RIGHT FRONT SEAT! SUPPLEMENTAL INFO FROM ACN 87348. COM COULD HAVE BEEN BETTER. STUDENT -- (INSTRUMENT) NEEDED A BETTER UNDERSTANDING OF PROCS. (HE HAD NOT FLOWN IN AT LEAST 6 MONTHS DUE TO AN EYE INFECTION). I AS INSTRUCTOR TAKE MORE TIME FOR PREFLT DISCUSSION ON RADIO COM ORDER USAGE.