Respond through the legitimate process and preserve the actual source and transaction evidence.
Do not alter the funding story
Identify what is requested and who holds it. A banking review is not a reason to invent a different source or omit an intermediate account.
Chiefly professional time and document retrieval: certified translations, archived bank statements, accountants' letters, valuations and additional legal hours spent reconciling records across jurisdictions. The share purchase agreement, the buyer's payment records, the company's financial statements and corporate registers, the tax filings reporting the disposition, and evidence of how the shares were originally acquired. Far enough to show that the funds were lawfully obtained by the deceased, using the records that reasonably exist: the estate grant and distribution, and evidence of the deceased's employment, property sales or savings from which the estate was built. Where funds come from employment income accumulated over many years, the natural evidence is the employment itself: contracts or letters covering the period, pay records, and personal tax filings for the relevant years showing income consistent with the savings claimed. Include the source-of-funds exhibits—the Canadian restaurant's sale documents, savings statements and tax returns—the evidence the capital has been transferred and placed at risk, and, if relying on the reduced threshold, the TEA designation.