Managed to get both United and Hawaiian miles for traveling OGG-HNL. The ticket was purchased through United- OGG to California and involved an interisland leg on Hawaiian. United only awards miles on Hawaiian when it connects to a flight to/from the mainland on United. When I checked in at OGG I provided my Hawaiian miles number to the check-in agent. When I got home I sent the boarding pass and retroactive credit request form to United and ended up with miles from BOTH programs. Just a note, the last few times I have flown interisland with Hawaiian or Island Air I've had to mail in the form to get my United miles (before I never tried to double dip). The downside (and I found this out the hard way) is if you leave the islands on Hawaiian, they will charge you for bags regardless of your status with United. It costs $10 for the first, and 15 or 17 (I don't remember) for bag number 2. Not sure if I will be doing this again, as I try to fly direct to Maui as often as I can (or if I do throw in an extra 500 mile leg I prefer to do it between LAX and SFO), but IT CAN BE DONE. If the hassle is worth 500 extra miles for anyone out there, that is how I did it. I assume this would work in the opposite direction (mainland to Hawaii) as well if you talked to a Hawaiian rep once you got to the islands and gave them your Hawaiian miles number.