Originally Posted by sfosuw

Just an update on this scenario. I telephoned MH BKK sales office and was able to speak with a very helpful Sales Executive who first confirmed on her computer system that MH DOES have an interline agreement with UA. She then informed me of the June 1st, 2016 Oneworld interline policy so officially it's a "No" for non-Oneworld interline. However, she offered to contact MH BKK check-in on my behalf to see what could be done in my situation (no visa for DEL). She emailed me back three days later with a detailed response from MH BKK Airport confirming that baggage interline is possible and they will do it as a courtesy as long as I allow enough connection time to avoid mishandling in DEL (2 hours +). To conclude, she emphasized that this is a "favor" on MH BKK's behalf and not to expect same treatment the other way around (UA to MH) or if journey starts from another station.

So, it is possible on a case-by-case basis so do contact them in advance and make prior arrangement.