Hi, Jonathan. Thanks for taking the time to reply to my message. There are different ways of spelling my surname, or so I've discovered lately. While I've been apt to spell is as "De Wind" all my life, I've met distant relatives who spell it as "DeWind" (the way you've described). The original spelling was "de Wind" - which is how it's spelt in some of the historical documents I've seen.
Yes, the person you found could very well be a relative of my grandad. Hopefully his heirs are still in Singapore, so that I can find them in the hope of finding out more about my own roots.
Thanks again. Please do feel free to write if you have even the slightest additional information.