Originally Posted by
ComplexAnalysis
In fact, you can call in, and book your original ideal itinerary AAA-MMM-AAA-ZZZ. Erroring out on the website does not mean it is not bookable. I'd suggest find the individual flights for that and give it to the agent so you can avoid the 'NNN' city in general.
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Originally I booked AAA-MMM-AAA as a simple region 1-region 2 roundtrip. When I called to add AAA-ZZZ at the end, the agent claimed it also errored out on their end. I suspect it would error out once it detects a roundtrip between AAA-MMM. Afterall, ZZZ is in another region other than AAA or MMM, so it is not the same case as in the wiki here.
You could also do this, however, you would *likely* be charged a change fee if the carriers change between the original NNN-AAA and the new one
I am exempt from change fee for award. The only thing I am concerned is whether the system would price out the miles needed correctly...