How are the Estates distributed if both husband and wife dies together (e.g. in a car crash) at the same time?

Additionally, in Singapore in the case where the order of death cannot be determined between 2 or more persons (e.g. simultaneous death), the Civil Law Act states that the older person is deemed to have died first. Even if you are older, it is entirely possible in accidents where your intended beneficiary dies very short after (i.e. in ICU). What this means is that you may end up still giving your assets to that beneficiary, only to have your assets be redistributed out based on his/her Will instead. 

Let's assume the case where a married couple with $100K each (without children) and both do not have a Will. If the wife is older, in the event of say a car crash, half her assets ($50K) go to her husband (who is presumed to have died later since he is younger) and $50K to her parents. For the husband, since at the point of his death he no longer has any spouse, his portion of the wife’s assets ($50K) and all of his own assets ($100K) go to his parents. This means that his parents ($150K) end up with 3x as much of the Estate than the wife’s parents ($50K). 

With a Will done through getArrange.com, this can easily be resolved by adding a survivorship period, where the beneficiaries have to outlive the Testator by an X number of days before receiving the Estate.