This really isn't a technical issue, it's more an estate planning issue.
The basic concern is if you die, everyone gets locked out. That is where a will, safety deposit box, and named executor come into play.

Whatever credentials and guides needed can be safely stored and upon death that will activates and the executor hands over the access to whoever you are needing. The safest assumption to make in these scenarios isn't that someone won't know how to access the information, it's that they won't even know that information exists.

You also have to remember that there is a lot of things to do after someone dies and that these people would also be mourning. So, with that consideration in mind, try to make the process as seamless as possible. Off-loading to an executor of the estate (someone who is not family) also lets those people close to you mourn without having that final burden.