In two separate conversations with the 1K line, United stated quite clearly that it's the originating carrier of the entire itinerary, not of an individual leg of the itinerary. Of course that's their interpretation which may not be quite the same as Hawaiian's interpretation. However, I can add that the complaint that I filed with DOT here:
http://www.dot.gov/individuals/air-c...t-comment-form
was sent the very next day to Hawaiian. I take that as a sign that the DOT agreed with the entire itinerary and not the individual leg interpretation.
In any case, it does seem to be a significant source of revenue for Hawaiian -- and one that they are not likely to change w/o more input from the DOT. Here may be a chance for FT members to encourage the DOT to help get things straightened out.