Can someone please explain this issue I am having with the SQ web booking engine?

What I want to do: Travel from KUL-SFO on separate days with a fewer than 24 hour stopover/layover in SIN.

Day X
SQ117 KUL-SIN

Day Y
SQ2 SIN-SFO

The SQ website Stopover/Multi-city search will not allow me to price that on separate days, but the One Way seach will allow me to price it provided that all of the travel is on the same operating day (which, is not what I am looking for). Is there a way around this? I have tried specific flight time (and not) for the multi city search but to no avail.

I have submitted a web feedback survey as well as an email to the North American web support address, but I have not heard anything back.

I have also called the North American web support desk and the person said that the website would not allow it for her either but that I could make the exact same reservation through the (800) reservations number. Of course, if I wanted to, I could book this on ITN or Travelocity or even call the (800) number, but I am just wondering why I cannot select these same flights on their own website. The fare and city pairs are obviously loaded because I can book the same itinerary for the same day.

Does anyone know why I am unable to do this through their website? Thanks in advance.