A-mao, actually the trust can work out perfect in this case...
because you can direct how your asset is distributed, to whom, when or at what age.
for an example, by using A-B trust, your net worth is 2mil, now lets say your wife passed away, assets are divided in 50-50, and your wife wish to pass her shares to the two kids, but not their spouses, when they turn 30.
so upon on her death, the assets divided in half, funded trust A and B, each with 1mil. let's assume, trust A is survivor, trust B is family, so, your share is funded in A, and your wife share is funded in B, and trust B is now irrevocable, meaning you can only executed the trust, but can not change her wishes.
now if you find yourself a 2nd milk, married and have another kid, your newly wed wants all the money goes to her kid, none to your older kids, and you stupidly agreed, but you still can not change what is already placed in trust B, meaning your older kids still get their share from their mom...
and further more, you can plan that none of your hard earn money will go to your kids spouses, or skip a generation totally, and pass the money directly to your grand kids..