If instead of booking flight only, convert into a BAH which does not penalise using different carriers as it awards you all the tier points for your spend.

So as long as it is possible to book a BAH with your preferred carrier you will get 1 TP per pound spent on the package.

BA are also not insisting on minimum stay to qualify

I’m suggesting this as an option to use other carriers as the flight-only option carries a shocking penalty for other carriers