You can either take NW once you get to NRT or KE from ICN.I flew KE from SIn to ICN in J this past summer and did not find the service to be all that great. The flight from SIN to ICN leaves at 1 AM (give or take) with food service being limited and abit strange (salmon for breakfast at 5:15 AM). If NW is flying their A330's to SIN, I would give them a try instead. I find that the seat is a bit more comfortable and their entertainment system (AVOD) is much better than KE movie loop.

If you plan on paying for the trip, you can credit SQ flights to Delta although I'm not certain about MQM's.

https://www.delta.com/skymiles/ways_...s/index.jsp#SQ

Good luck and enjoy Singapore...