I recommend this book. Very simple steps and templates for free to answer cryptoassets inheritance planing from Pamela Morgan: https://www.amazon.de/Cryptoasset-Inheritance-Planning-simple-owners/dp/1947910116
To lower risks in deadly events.
Store your keys on multiple encrypted hard drives. Give the drives to multiple different lawyers to be held in trust for your heirs. Give your heirs the passwords.
If you're really paranoid, you can use multiple layers of passwords and something like Shamir's Secret Sharing to make it impossible for any one heir to corrupt any one lawyer and steal everything. Make it so that at least two heirs have to cooperate, or at least two lawyers, or both -- depending on how many heirs you have, and how many lawyers you want to pay to hold on to your drives.
Note also, don't use SSDs or flash drives, use plain old ordinary spinning-disk hard drives. Flash memory dies if left unpowered for long. Even a few months can be enough to render it useless.
There's a book out there about cryptoasset inheritance. I don't know if it's primarily technical, primarily legal, or covers both.
Haven’t read it; I just googled “crypto estate planning” (which google had an autocomplete for).
Also make an inheritance plan for the bitcoin so you can pass it on if you ever need to! I used the book Cryptoasset inheritance planning to make mine. So glad you were able to inherit his bitcoin though and sorry for your loss.
Agree with the books listed. Loved Internet of Money. I’d also recommend Cryptoasset Inheritance Planning so your seeds are securely stored and you have a plan should something happen to you.