Appointment or promotion records for the person taking over, signing authorities updated with banks and counterparties, revised organizational charts, and correspondence showing they now make the decisions. Ongoing foreign invoices, payroll and contracts show the business continued under their management.
Update the outward-facing records
Internal notes are easy to write and easy to discount. The stronger set is what the outside world sees: who signs contracts, who is named to clients and suppliers, who authorizes payments. Update those at the same time as the internal chart so the two agree.
Advisers can assemble and cross-check the set; whether it supports the classification, and how it should be presented, is for licensed counsel. Add one class of record that costs nothing to preserve and is difficult to recreate: the ordinary correspondence that shows the successor deciding things. A supplier told about a new approver, a client introduced to a new account lead, a bank mandate updated, an insurer notified — each is dated, made for another purpose, and unarguable.
Ask the successor to keep a simple running list of the decisions they have taken alone, with dates, rather than reconstructing it later from memory and mailbox searches. Hypothetical example: a hotel group's incoming general manager keeps a one-line note of each contract signed and each escalation resolved without reference upward, and eleven months later that list, cross-referenced to the underlying documents, is more persuasive than the organisational chart drawn for the file.