Can't add passanger to flexible BAH booking - other ideas? Please can you help with the below edge-case?

Scenario:

We're flying LH with BA in the autumn.

There's a 1/3rd chance I need to cancel due to work commitments, so flexibility is important.

I previously made 3 bookings:
* 2 booked in CW,...
https://www.flyertalk.com/foru....m/british-airways-ex