A rather specific luggage question

[estate]

I'm booked on a RTW trip with Swiss (using QF for the first and last legs) in J that includes a BA Y flight and have a question about the luggage allowances.

The trip is SYD-NRT-ZRH-GVA-LHR-ZRH-JFK-SYD. GVA-LHR is with BA in Y, and is on a seperate ticket but on the same itinerary.

I called Qantas and asked about baggage, and they were quite clear that I my allowance is 2x 32kg bags for both QF21 and QF108.
Swiss also advised me that my allowance is 2x 32kg bags for all the flights I have with them.
I logged into BA just to check the itinerary and had a quick look at my baggage allowance - it said 3x 23kg bags!! On a Y flight!

I called BA and asked for clarification, and the girl didn't believe me at first until I told her specifically where I'd clicked on their site to find out. She advised me to just turn up at GVA and "try my luck". But it'll cost me GBP85 if they turn me down.

Has anyone had any experience flying on mixed J/Y itineraries (especially with BA) and the luggage allowances that go with them?

 

[serfty]

Generally, most non LCC airlines permit the highest available baggage allowance of any one segment in a single booking/PNR for the entire journey.

 

[estate]

Thanks serfty. I called my travel agent asking her to clarify, and said this what I'd heard. She called BA and they said no, it's one 23kg bag, but since it's on my BA itinerary as three, I should definitely try my luck. (I'll print that document and take it with me to the checkin desk at GVA)

She also called LX and asked them to clarify their baggage rules - apparently my ticket is technically not a RTW ticket, and I don't get the two piece system for the outbound legs of the journey. That goes against nearly everything I've read on here - different baggage allowances on one ticket, within one itinerary?? Very odd.

However she came up with a solution that suits me perfectly: switch my outbound flights to go via the US, so I now have a mammoth SYD-JFK-ZRH-GVA start to my holiday. Since 107 leaves before 21, I end up in GVA earlier than previously, and I earn even more miles and SCs since it's a longer flight with QF. That's actually preferable to my original itinerary, so I won't fight what I think is an incorrect interpretation of the luggage rules.