Selecting seats on Hawaiian when booking through OTA
 

This isn't really a question, just adding information, that someone else may find useful in the future, as I was unable to track down anything online to help.

I'm in the UK, and wanted to book HA flights HNL-PPT roundtrip. I didn't want to pay in USD and be hit with FX fees and poor credit card exchange rates. I was concerned about booking via an OTA and not being able to select seats, so I contacted HA, and they said the only way to pay in GBP would be via a third party, but if there were any problems selecting seats, to contact them again and they would help.

I booked via Opodo, which offered selection during booking, with every single aisle seat blocked (even though the HA seat map was practically empty), so I skipped the seat selection and made the booking. Unfortunately the HA website wont allow seat selection for the booking as it was made through a third party. I contacted HA again through the web chat facility, and they were eventually able to assign me with two seats together at a window pair (though after trying to put us in a middle middle pair).

YMMV with other third parties of course.