For example, I will worry a lot to leave my inheritance to my wife. She’s not very independent and know nothing about financial stuff. Don’t even know how to pay bills etc.
If leave her with money, scare she kena scammed or wasteful. Worse is she don’t work and spend money carelessly. After few years, maybe before the kids grow up and start working, the money would be gone.
If you're really worried about this scenario then Henry made some suggestions, and I'll expand on them. In no particular order:
1. The CPF Enhanced Nomination Scheme is available. Your CPF nominee(s) can receive deposits into their CPF accounts instead of cash. Standard account limits apply, and the residuals (if any) will be distributed to your nominee(s) as cash. The CPF ENS is mostly about assuring that your heir(s) will have CPF LIFE income streams in their futures.
2. Yes, you could set up a trust, although that's a bit complicated. You might be able to do this fairly simply together with a charity in something called a "charitable remainder trust." For example, you could instruct the charity to invest your donation in Singapore Government Securities with a minimum of 10 years until maturity. All coupons (or maybe 99% of coupons, so the charity can cover its administrative costs) must be paid to your survivors as long as they live, and all maturing SGSes must be reinvested in SGSes. When your final heir is deceased the charity receives all remaining value in the SGSes.
3. I haven't checked into it, but you might be able to leave instructions that (for example) a substantial portion of your estate should be used to buy a single premium immediate life annuity from a life insurer in Singapore with your wife as beneficiary. And/or additional single premium immediate life annuities for other members of the household. Preferably escalating life annuities. This way they'll each have reliable lifetime income.
So, if parents still young and healthy, and financially prudent/savvy, I may consider leaving my inheritance to them with explicit instructions for the money to be used on the kids.
That's a big "if," though. You ought to anticipate that a parent will pass on well before the end of the relevant time period that you're trying to support. I think in general it's better to set up a more reliable arrangement.