I'm so happy a friend told me about this site a few days ago! I used the link at the top of this thread and was able to get seat assignments for award tickets booked via UA.

Does the link still work? I just tried with my United e-ticket number but keep getting the error. I used IE and Chrome to no avail. Tried my name+MR and doesn't work either.

Anyone have any luck with accessing their reservations with a United codeshare?

Thanks.

I was able to access and reserve seats and I have award tickets issued as UA codeshare.
I called UA to obtain the 6-character Asiana confirmation number. In addition, be sure to enter your first name exactly as UA has it on your reservation (may include initials and/or MR/MRS/etc.).

Asiana says it is not possible to view a UAL Mileage Plus award ticket on their website until 72 hours before departure.

You're right that I can't view the actual reservation - I get an error response. However, when I use the link on this thread I am directed to the seat assignment option and I am able to get the pop-up window that allows me to assign seats.

I was finally able to log in but it was more complicated than it needed to be. Hopefully my situation will help others. I booked a multi flight through United that included flights with Asiana and Air Nippon. I was able to select seats with Air Nippon by calling their US number. After I selected the seats, they emailed me a different Reservation number than the one United provided me. Using that different number I was able to log into Asiana to select those seats.

So it sounds like the Asiana flight was a codeshare of Air Nippon, rather than United. I wouldn't have been able to login to Asiana without getting my Air Nippon seats assigned first. The reservation number United gave me did not work with Asiana, nor did my eticket number. Only thing that worked was the new Air Nippon reservation number.

This worked for me as well once I figured out the pesky pop up blocker on my Mac :-)

Is there anywhere in this forum or OZ's website with a rundown of what the seats are like in each class on each aircraft? I'm looking at an itinerary for BKK-ICN-ORD-vv and would like to know what I'd be signing up to.

Another data point: I purchased a C-class RT BKK/LAX on Priceline for a friend of mine. Could not change seats online with the OZ PNR, but a phone call found a very helpful young lady who fixed everything.

Yet another data point: I hold two reservations in business class from LAX to SIN via ICN -- one purchased with cash and the other with miles through UA Mileage Plus. Using the online tool posted above, I was not able to select a seat for the one purchased through Mileage Plus using the ticket number (I do not have the OZ record locator). I was, however, able to select a seat for the other reservation using the OZ record locator, even though it was purchased through a travel agent.

Next step is to call Asiana to try to get seats together.

Contacted Asiana regarding this issue,

If your flight departs within 48 hours & bought it form United:
Use Asiana online checkin

If your flight departs outside of 48 hours window:
Need to contact Asiana customer support in order to reserve/change a seat

The link worked for me when I was choosing my seat for an OZ flight booked on a paid UA ticket. It didn't work when I was tried to pick my seat for a UA codeshare flight operated by OZ. I ended having to call Asiana customer service; took only 5 minutes or so.

Correction to the wiki above:

The wiki states that the name format should be:
LASTNAME FIRSTNAME+MI+MR

In my case at least, that was not correct.

I booked an award ticked using United miles, with a couple legs on OZ. My name, in United's original reservation was Public/John Quincy.
According to the wiki, the format would be PUBLIC JOHNQMR but that failed

When I tried it as PUBLIC JOHNQUINCYMR only then did it accept it

So, at least in my case, where the original reservation contained my full middle name, then the format should be:
LASTNAME FIRSTNAME+MIDDLENAME+MR

Hope this helps someone.

Just wanted to chime in on this. I have two seats booked in OZ J for January 2016 JFK-ICN-HKG via a United award redemption. I was unable to select seats online, either via United or Asiana. However, this was completed quite simply by calling Asiana reservations, giving them the UA record locator and requesting the seats. Certain seats were blocked (i.e. the small business cabin seemed to have quite a few that were not reserved but blocked), but was still able to snag two together in row 11. Additionally, asked for a confirmation itinerary from OZ and received two emails, one confirming the seat selection and one with an attached itinerary.

does anyone know why Asiana is offering availability to be booked in first class cabin under business class service? I just went through the advanced seating website and for a flight from ICN-HKG via A380, they offered options for 1st or 2nd floor, intimating that the first class seats were bookable. Do they offer biz service in first class cabin???