I've tried everything... Checkmytrip/Amadaeus, Sabre, etc...
My trip is 50% NH and 50% TG. I have my NH PNR and I was able to view all of my NH flight information online and I even called and had them add my itinerary to my ANA club membership so I could always just look at it on ANA's website that way.
Thai offers no apparent way to look at the TG portion of my trip online at all.