Re: HKG-DEL-LHR, UA treat it as 2 sectors, HKG-DEL and DEL-LHR as HKG-LHR is not a legal routing on UA (they do not have traffic rights), you may need to check if it is legal for you to do HKG-DEL-LHR within the context of that trip, it likely is as it is a RTW fare, but be careful.
I am doing it myself, but am allowed to transit DEL as UA has rights from oz->lhr and I am originating my trip in oz on that day.
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UA 1K MEL
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