Hawaii-based Airlines - Seat Selection on HA

In December 2011, I booked awards on Continental from San Diego to Palau and a partial return, SAN-LAX-ICN-ROR-GUM-HNL, Nov 2012. I got a separate CO award HNL-ITO and purchased a flight on co.com KOA-OGG. The inter-island flights are on HA, with HA flight numbers. The PNRs were CO, now UA, the ticket stock is 005, Continental.

The PNRs and ticket numbers are "not found" on the HA website. Should I call UA for seat assignments? No big deal if I will just get a seat at the airport, considering the flight durations, but if I can get seats, I would like to. Calling HA with UA PNRs and ticket numbers will surely be futile, no?

Update: I called Hawaiian, and got seat assignments for HNL-ITO, no problem. The CSR gave me the HA PNR so I could view the reservation online.

The KOA-OGG segment is actually on Island Air (WP) not HA, and they don't preassign seats.