If you just book a simple open jaw ticket on QR or CX, as I suggested way above in post #7, then your bags will be checked all the way to DPS and your return will be from SIN and everything will be on the same ticket and you'll be on oneworld carriers the entire way.

If you actually want to stop in SIN on the way there then just book a roundtrip to SIN and a separate ticket SIN-DPS.

But as myself and everyone else has said, if you don't want/need to stop in SIN on the way there, then there's absolutely no reason to try to force a connection in SIN on the way there and deal with separate tickets etc. That doesn't make any sense.

(I am giving you this advice as someone who has been to SIN many times and travels to SE Asia from RDU no less about 3-4 times per year)