Start with a Coldcard Q (Seed XOR backup). Distribute the Seed XOR pieces geographically (with redundancy). Choose locations to minimize the risk of collusion. Your work friend and out-of-country cousin are unlikely to collude, especially without knowing the passphrase.

The Coldcard Q can be shared among family members. Each can use their own BIP-39 passphrase for a unique wallet and BIP-85 Deterministic Entropy for generating secure seeds and passwords. They can also type secure notes on the Coldcard Q, decryptable only with their passphrase.

For estate planning, create a dedicated passphrase for encrypted notes. These notes should include instructions for accessing your Bitcoin and fiat accounts, details of other passphrases, and BIP-85-generated passwords. You can now leave the encrypted note and passphrase, along with instructions for combining the Seed XOR pieces with a lawyer, or, transfer it via a dead man’s switch. The information being transferred is fairly useless until the Seed XOR pieces are combined, significantly minimizing trust, and leaving many more options for transferring this information upon your demise.

In the meantime, family members can use the Coldcard Q without worry, protected against natural disasters, political upheaval, or other emergencies. A new Coldcard can be recreated from the Seed XOR pieces, and individual pieces can be recovered one by one (without needing them all in the same place at the same time). Additionally, the Key Teleport feature allows remote recovery of backup pieces.

Each family member only needs to remember their passphrase (or store it securely). With this, they can recover everything, and once again be able to decrypt their personal notes (always being decrypted on an air gapped device).

The only missing piece? Coldcard Q exporting encrypted notes. Currently, notes are encrypted while on the Coldcard, but can only be exported unencrypted. This is me trying to drum up support for an encrypted export feature (using deterministic entropy), or for some other hardware wallet manufacturer to implement a similar feature. I think this missing piece would be very useful in the estate planning toolkit.