Originally Posted by
corporate-wage-slave
It's just -3 days to +14 days so long as there is cabin space and assuming BA or IB operated services. You can only move it outside that window if there is redemption availability, so it would save the £35 change fee but that's the only benefit.
I was successfully able to get rerouted on AA flights as well, though this was probably due to the extra extra flexibility during peak covid times.
original booking was done with 2-1 chase voucher therefore all on BA flights, but when a leg was cancelled I was able to move the whole journey about 10 days forward and LAX-LHR-MXP on BA became LAX-JFK-MXP as J on AA