Thanks to help from those on this thread I believe I am now in a position to rebook my DONE 4 booking ex Cairo after flying the 3 first legs. My objective is to maximise BA Tier Points and Avios and minimize taxes and surcharges:
First three legs to be flown in December:
CAI-CMN-JFK-LAX (stopover)
Planned rebooking:
LAX-ANC (stopover) - DFW-GRU-JFK-HKG-DPS (stopover) HKG-CGK (stopover) - HKG-DOH (stopover)-HEL-LHR-CAI
Total flight segments 16
Based on my understanding of the rules this should work but just wanted to confirm I am not missing anything obvious before I make arrangements to nest the 13 legs into my next Tier Point collection year by booking flights back from LAX spanning the period between the first 3 flights and the proposed 13 flight rebooking. Also to confirm except for recalculating fees and surcharges there should be no further fees.
Thanks again