The weight uplift definitely used to be for the status passenger only, while the quantity uplift was for everyone. I particularly remember checking in 2x31kg (very nearly) at DUB and the checkin agent paused, thought about it, and she and I said almost at the same time "the increased weight allowance is for me/you only" as I lifted on the other 2x22kg bags. We had been shopping...
Weight and quantity uplift for all on the itinerary for a lower status level is quite generous of BA. A family holiday led by a silver cardholder could load up a lot of stuff that way.
However the BA website has been saying that the whole party gets the weight uplift
since at least May 2016 but
was not saying so in 2015, at that point it was only quantity uplift.
Personally, I would be bringing a reference to the web page, especially if checking in anywhere other than LHR. It could be particularly interesting to apply this wording to other carriers downroute on a mixed carrier ticket based on BA being the Most Significant Carrier and controlling the luggage allowance. Battlefield dispatches are welcome
