Share registers, articles of incorporation, purchase agreements and any holding or trust documents that show who owns each entity and in what proportion, supported by evidence that both companies are actively doing business.
Ownership on paper, operations in evidence
Hypothetical example: everyone at the Coaldale plant says the American facility is “ours”, and the accountant's file shows it is held by a numbered company owned personally by two shareholders. Both statements can be true, and only one of them is what a reviewer reads. Collect the incorporation documents for each company, the share register or membership ledger showing current holders and percentages, any shareholders' agreement, and the purchase agreement for the U.S.
plant. Where a holding company sits between them, chart it so the ownership line can be followed without explanation. Then prove operations: leases, utility accounts, customer invoices, payroll registers and photographs of the working facility.
A relationship that exists only in an intention to reorganise is not yet a qualifying relationship, and reorganising after filing is far more expensive than doing it first.