I have an upcoming trip YFC-YYZ-YVR-ICN-KIX in PY. Unfortunately, the return trip KIX-HND-YYZ-YFC is booked in Tango. Would it be possible to reroute the return trip via YVR on the day of departure? I understand that Tango fares will not available at that time. I would have to rebooked in Flex which will add about 3,500 miles to the trip.

Advantages:
- more miles
- possible upgrade to PY
- arrival in YFC would be the same

Disadvantages
- cost $100 (seems a small price for 3,500 status miles)
- seat selection may be poor
- may have to leave 2 hours earlier (no big deal in this case)

Is it possible to do these changes over the phone? If they have to be done at the airport, it may be difficult to do at KIX (I assume there is no AC agent).

Would it be possible to change the departure from KIX to ITM? ITM has a better connection to NRT—actually an AC codeshare.