It depends on who the fiduciary is answerable to. A trust or family office needs an arrangement a lawyer, an auditor and the next generation can each understand: assets titled to the entity, segregated, with more than one party required to move them and an examination report on the custody operations. Multi-institution custody and qualified custodians are built for that; the deciding columns are entity support, insurance basis and the independent examination.
Fit engine rules 0.1 (1 Nov 2026), with this situation's inputs preset. Adjust the inputs to your own case. Proof of Custody is published by Onramp Bitcoin, which appears here where its custody model fits and is scored by the same methodology as every other platform.
Recovery: Identity and authority documents to the institutions; no device, seed or ceremony on the heir's side.
Single point of failure at this size: one device, company or person can lose the whole holding.
Recovery: Identity and authority documents to the custodian; the custodian's own succession procedure.
Fits only where the provider documents an assisted inheritance path the recoverer can follow with support; otherwise the arrangement becomes a puzzle box the day you are gone.
Recovery: Locate the devices and seed backups, run a signing ceremony with the provider's key; or, where the provider documents an assisted inheritance path, follow that path with the provider.
Single point of failure at this size: one device, company or person can lose the whole holding.
Recovery: The brokerage's beneficiary or estate process; no keys involved.
Excluded by the rules: Self-managed multi-vendor multisig (Recovery floor: this model requires the recoverer to run a hardware wallet and handle a seed phrase, and the person you named cannot be expected to.); Single-signature hardware wallet (Recovery floor: this model requires the recoverer to run a hardware wallet and handle a seed phrase, and the person you named cannot be expected to.)
These are custody models that fit the situation described, by Proof of Custody's published rules, version 0.1 (1 Nov 2026). They are not a recommendation to buy, sell, move or hold anything, and not legal, tax or estate advice.
A family office holds bitcoin on a trading venue and wants professional custody without adding operational work internally.
Bitcoin belongs to a trust, LLC or corporation, and the arrangement has to recognise the entity rather than an individual.
The buyer holds more than $10M and needs the arrangement to survive scrutiny from a board, an auditor and an insurer.
Agent tool: fit_custody_setup. Primary sources: poc-scores. Refresh: scores monthly. All routes.
Free, read-only, no key. Every answer carries its source URL, as-of date and the publisher disclosure.