Originally Posted by
MegatopLover
To the OP, you can probably book an open-jaw itinerary, such as KE USA-ICN-BKK and KE SIN-ICN-USA then buy a separate one-way ticket on another airline to close the open jaw. There are lots of flights on lots of airlines between HKG and BKK and BKK and SIN, plus heavy competition on SIN-HKG.
KQ and CZ are both part of Skyteam and could be included in the award itinerary. Availability is pretty easy on CZ, so it seems silly to purchase a revenue ticket (likely on an LCC in coach with a terrible seat pitch) to close an open jaw when that isn't necessary to cover the OP's desired itinerary.
I wasn't aware that SQ couldn't be combined on the same award itin as a Skyteam award with DL miles, but they do have a SE Asia award for 25/40/60 Y/C/F, so leaving the US isn't the only way to use SQ. I suppose separate nested tickets could be done, but still with the CZ option and no visa required for transit up to 24 hours in China it seems unnecessary.