ok, CX in TPE told my agent that I cannot reroute last flight of xONEx from HKG-TPE to HKG-PEK-HKG-TPE, because "there is only 1 segment left".

I just called CX in HKG directly. they first said I cannot do it because I am only allowed two stopovers - then I explained to them that I am not going to stopover anymore in PEK and HKG, all under 24 hours. then they double-checked twice (with whom? I'm not sure) and called back twice and said I cannot do HKG-PEK overnight <24 hours then PEK-HKG, HKG-PEK-HKG needs to be same day (or even, they also mentioned, the first flight available - but seems like this is less stringent). I said I traveled with at least a few of these xONEx tickets every year and I don't think there's any rule about transit being same-day or first-flight available. they are still checking again and will call back later...they said "this is from the rule of these tickets" - I told them if they are able to show me that the rules indeed are like this, I am happy to comply, but not now yet.

but is there really any authoritative source they can refer to (or I can ask them to call) in cases like these, instead of making up all the rules themselves office by office ? or, since this ticket was issued by CX originally, do you think AA RTW desk would be willing to help me reroute ?

thanks.