I have decided on a 5 fund portfolio consisting of
SPDR STI ETF – ES3.SI
iShares Core MSCI World UCTIS ETF – IWDA.L
iShares Core MSCI AC Asia ex Japan Index ETF – 3010.HK
Nikko AM Straits Trading Asia ex Japan REIT ETF – CFA.SI
Nikko AM SGD Investment Grade Corporate Bond Fund – MBH.SI 10%
This is way too complicated. All you're doing with the pair of Asia ex Japan funds is (a) adding investment costs, (b) overweighting companies that happen to list in a specific geographic region's markets (when you already have regional overweighting in the STI stocks), (c) overweighting a specific sector that you're already overweighted in if/when you buy your own primary residence in Singapore.
Keep it simple! You really, really don't need to make things so complicated -- it's completely unnecessary. If you're concerned about "missing" "Asia" (you won't) then just use VWRA instead of IWDA if you want to pick up "emerging markets" such as China, and you're all set.
Opinions diverge, but my preference is to cap the STI stocks at 20%. So an allocation of something like 20-60-20 (ES3 or G3B-VWRA-MBH) would be fine from my point of view.