I am flying from Copenhagen to New Zealand via LHR next month on two different airlines. The CPH-LHR leg of the flight is operated by SAS airlines and the remainder is Air New Zealand. The baggage allowance for the first leg is only 20kg, while my Air NZ allowance is 2x23kg bags.

The flights were booked together through Air NZ and are on the same ticket, but under the baggage allowance of the SAS flight it says I must refer to the operating airline. Will SAS honor the Air NZ allowance?

I emailed SAS and they said as they are the initial carriers, I must follow their baggage rules. But Air NZ says that their 2x23kg baggage allowance applies to the whole trip.

I'm still waiting to hear back from SAS a second time, but are there any international regulations regarding situations like these where connecting flights have different allowances? And which one should I follow?