I have similar issues with UA - and as you have learned UA doesn't have the most robust processes or systems.... I would keep watching it every day - NH changes award seat availability quite frequently - so keep watching and I bet there is a good chance it will open up again... I was in BKK in December and before that I was checking multiple times per day and NH would be there one day and gone the next and then back the next day - in economy and business - so you still have a shot! Also - TG may open up space closer to your travel dates - and let me tell you that A380 from NRT to BKK is a sweet ride in J or F - so if they open up seats you could change to them for the both of you.... Just some options to look for - I know it's stressful but don't give up!