I don't think that's what he wanted to know. He's concerned about how his relatives would access his funds if anything happened to him.

I can only give you one tip here that I've used myself. Make a copy of your most important data and give it to the person who would be your heir in case of your death. You could for example create a USB stick with photocopies of your codes/seeds etc. on it and encrypt it with a password that only you two know. Alternatively, you could of course give this data to a lawyer who would handle your estate ... should you have one.

I think it is very good to make arrangements for such situations, you just don't know what will happen tomorrow. Especially private keys and co. could be irretrievably lost if you don't store them in a secure place where a third party knows about them.