If you have a few children, you could try using multisig, but then there's that one of your children dies after you, but before they can share the money.
You could also use a time lock, but then, it doesn't mean you'll time it well enough. You're 50 and you have a 10 year old child, so you lock your coins for another 5 years, but you're still alive, so you keep going, finally you lock it again and die a year later, so your child will have to wait 4 years? That's pretty harsh.
I guess you have just divulge the weakness of using some of the technologies suggested. A situation where one of the heir dies when his signature is needed to access the wallet will be disastrous for the others. Unless there is any other way out of this. I read where @JayJuanGee suggested integrating the services of a hacker as a contingency plan should anything go wrong when the heirs will be accessing the wallet.
I'd put the instructions and seeds in a capsule and hide it somewhere. I'd give the location to someone that I trust, but make it hard for them to break into it. Let's say you have children and you tell them where the capsule is, but it's under a concrete floor in your living room, so they'd have to use an electric tool and need a whole day to uncover it. They won't do it wile you're alive, but should have no problems getting to it when you're gone.
This is pretty amazing! This is feasible and more like a good option because there is very low chances that your children will break the floor while you are still living in that same house. However, it becomes a bit complex when you have that one child that is adventurous and stubborn and who will not blink an eye to break the floor while you are on vacation or something like that
. Anyways, the chances of this happening is minimal since it is expected we raise good and loyal children that are worth keeping inheritance for.
Perhaps you can share the location to two different people that you trust with instructions to only tell your children when you are gone. The information should exclude the amount so that those you trust will not buy the building when you are gone by the time they know the value of what is there.
All the same, this is one of the best suggestion I have seen so far as it eliminates the chances of technological failure and information leakages.