When you involve a lawyer you have already revealed all your worth to a fellow human being you knew nothing about, there are many corrupted lawyers in my country, I don't know about others but what do you think about this?
At some point in life we have to trust someone who's not ourselves, we can't live without trust and when I hear stories like this I somehow blame the person that was involved in this accident because some of this cases can be easily avoided but we don't do things rightly. We now have law firms that can handle our wills and we should stop trusting just one lawyer, pay that extra fee and get a firm to be incharge of your will if you're that wealthy that'll require you to be killed to take over your wealth and don't do things alone. There should be some witness that'll make it difficult for them to plot evil against you and also treat your lawyer well. I know some humans are just evil that no matter what you're paying them, they'll still plot evil against you but paying people well take away most of this threats.
Imagine where by a hardware wallet is created with the set time capability to release Bitcoin for your children? I have never seen such but I think it's doable, sorry if I make this sound easy as I am not even a developer
Things like this are already in existence so I won't have to go over them as I believe justice has been done by those that have commented before me but I also want to stress that although living our wealth in Bitcoin to our children is encouraging but if we have kids that haven't matured to the level of understanding how to operate a wallets and get the Bitcoin when you pass away (like your heirs are still children then there is nothing wrong in going the traditional way by giving them a fortune in fiats) or better still make a paper wallet and keep them in a valut that the key to that, will be in the will and they can get access to it after you pass away. This goes back to having a trusted lawyer or firm to oversee your inheritance wills and not hungry random lawyers.