I'm looking at booking a journey with bmi / United from MAN-LHR-ORD-MSP in Y. As a BD*S, I gather I would be entitled to 20kg additional luggage allowance on the bmi flight, so a 40kg total. United have a limit of 23kg in economy. However, I also see on their web site, "If a ticket includes both international and domestic travel on two different airlines, then the rules of the carrier initially accepting the baggage will apply." Does that mean I'd get the full 40kg allowance for the entire journey? What about with the ORD-MSP connection (the full journey would all be on one ticket)?

Sorry if this is a question that's been answered many times before, I couldn't find any obvious reference to it.

Thanks!