Wife holds a key, a friend holds a key, I hold a key. Only I know the identity of both which is fine until I’m dead. At which point how is my wife or my friend supposed to know what to do? Well depending on how much I trust them if I wanted some level of additional security instead of leaving them with keys directly I could leave them each with an envelope with instructions on where to go to find keys and I could have the envelopes be tamperproof so I can check and know if somebody is going hunting for keys before I’m dead.