Originally Posted by
corporate-wage-slave
It's probably just me but I find these mysterious XXX routings very difficult to make out, so it's probably easier for me to put some routing in there even if it's not accurate. But let's say you are:
LIS-MAD-NCE where MAD-NCE is Nostrum. Then yes you can replace it with
LIS-LHR-NCE on BA metal.
You can't change the start airport, or the end airport. You also could not go via LHR if your original time in MAD is over 24 hours since that's a stopover rather than a layover. This would need to be a 125 ticket.
Yes, exactly - think original routing as something like FRA-MAD-MEX (FRA-MAD on YW coded as IB) and replacing it by FRA-LHR-MEX (where FRA-MAD is not actually cancelled but you worry it might be). I presume call IB to make the change then (booked directly on IB website)