My only comment so far is that KUL-HKG-SIN is a bit of a waste of two coupons which you could probably better use in South America. You have already visited HKG previously, and KUL-SIN is either a cheap LCC flight or the train (if you are into that sort of thing).

To do all of those places in SAM you may have to buy one or two extra segments - which you can do so long as you stay under 20 in total (another reason for not wasting 2 on KUL-HKG-SIN).