I have a QF award ticket with 4 sectors, AA.WS.WS. AA. AA are in Business and First which are 2x32kgs free. (I'm in Y on WS sectors but not by choice; you can't choose premium on WS when using QF award points bookings)
My QF issued tkt states: "American Airlines baggage rules apply". It's actually a law in US and Canada I don't think WS has room to move in our cases? I have printed out the below and ready to show the dragons at WS check-in. Let us know how it works out for you and so will I. My flights are in 2 weeks.

Guidance Document for Airlines
Interline Considerations on Baggage Standards

Copyright IATA 2020
In the current environment, a single set of baggage provisions applies to an entire itinerary. The
provisions that will apply are either selected following regulations, following the industry default
selection provisions (IATA Resolution 302), or are selected by bilateral agreement.
The main standard processes that currently determine the application of baggage provisions for
interline journeys are:
• IATA Resolution 302 determining which rules to apply in an interline journey, for each
checked portion and defining the concept of the Most Significant Carrier (MSC).
• US Rule for travel originating in or with the destination to either USA (U.S. DOT Regulation
399.87) or Canada (CTA Order 2014-A-158). The Governments of these nations require
that a different concept applies. This concept states that the provisions of the Marketing
Airline on the first coupon of the overall ticket shall apply to all flights on that ticket.