The receiving firm's account-opening file and the transfer-in confirmation usually show the positions and cash that arrived, and the date. Pair that with the tax slips or returns that reported the same holdings. Two independent records describing one transfer are stronger than one perfect statement you cannot obtain.
Building a substitute record set
Ask the current firm in writing for its full archive, including imaged statements it inherited. Keep the refusal letter if it cannot produce something — an explained absence supported by secondary proof reads very differently from silence. Missing documents will not always end a case, but they can lead to a request for evidence or a refusal, so close the gap before filing rather than after.
The will or intestacy declaration, the death certificate, the estate inventory, the notarial or court documents naming beneficiaries and shares, the final estate accounting, the distribution record and the executor's contact details for a statement. Where the amount is significant, questions about how the deceased accumulated it may follow, which can mean property records, business documents or tax filings from the estate. For lawful source, the file goes back further: how the investor originally acquired the industrial-supply firm's shares, whether by founding it, buying it or inheriting it, with corporate records and personal tax returns from that period.