Full fare business class allows unlimited stopovers and there is no charge to change. So yes, you can do this. The flights from Honolulu to the mainland will be First Class since they are 2 cabin aircraft.

11 STOPOVERS - UNLIMITED STOPOVERS PERMITTED. A STOPOVER
OCCURS WHEN THE PASSENGER DOES NOT DEPART AN
INTERMEDIATE POINT WITHIN 24 HOURS.


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