For the truly paranoid, I advise to put an additional copy in cold storage at a bank vault at bank A. Print the GPG private key and passphrase out and put it in

For the truly paranoid, I advise to put an additional copy in cold storage at a bank vault at bank A. Print the GPG private key and passphrase out and put it in a bank vault at bank B. Handle permissions to access these vaults within your family as you like it. Bank A shouldn't be in the same region/area as bank B in case a desaster strikes and floods the vault(s). Then play that scenario through whenever you update your keys/data.