Originally Posted by
Dave Noble
The 1st carrier's allowances on a multi carrier itinerary are not necessaily those that apply
It is the POLICY of the 1st carrier that applies - that carrier may choose to apply its own policy or defer to the most significant carrier
It seems unlikely that it is a through ticketed itinerary given the difference in classes
For tickets where the furthest ticketed destination is in the US or Canada, this is probably better clarified as the first marketing carrier on the ticket involved.
For example, if it's a return ticket that originated in SYD and the first flight was SYD-LAX then the marketing carrier for SYD-LAX gets to choose to either use their own policy, or use that of the MSC.