Originally Posted by NM
Where you may have a problem is that an open-jaw or land segment is also considered a stopover. And since you started in DRW, you technically finish in DRW. However, you can finish with an open-jaw by stopping in BNE, but that last stop into BNE is really a stopover for the land segment back to DRW. And you have already had two stopovers in the country of origin, being the land segment BNE-SYD and the stopover MEL-BNE-SIN (both in BNE). So technically that is three stopovers in continent of origin

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There should be no worries in regards to a third stopover as the ticket is issued open jaw - thus there's no need to return to the point of origin. This is outlined in the rules:
D.TRAVEL MUST BEGIN AND END AT THE SAME POINT
EXCEPT
ORIGIN - DESTINATION SURFACE SEGMENT PERMITTED
WITHIN COUNTRY OF ORIGIN.
E.OPEN JAW AT ORIGIN IS PERMITTED PROVIDED IT IS
WITHIN THE ONE COUNTRY.
I'm currently on a ticket that was booked BNE-SIN........LAX-SYD(stopover) SYD-AYQ (stopover) // DRW-SYD. There was no need for me to return to BNE or have that counted as an additional leg or stopover (that would take me over the 20 segment limit).