I assume I know the answer to this will not be positive, but i thought i would ask the group anyway for experience...

I have a booking LHR-DXB-SIN with a 5 day stopover in DXB. Booked as Business Saver (O) class, so i can only upgrade when checkin opens 48 hours before the LHR-DXB flight.

Currently both sectors LHR-DXB and DXB-SIN are available in F reward class.

My question is when checkin opens for LHR-DXB will I be able to upgrade both sectors (for 68,250 miles if F award class is available) or will they be treated as separate sectors and charged 50,700 and 65,910 respectively.