Ownership documents prove it. Share registers, share certificates and incorporation records showing who owns what percentage of each entity, together with evidence that both are actively doing business.
Ownership records, not organizational charts
Hypothetical example: The relationship required is parent, branch, subsidiary or affiliate, and it is a question of ownership and control rather than of commercial cooperation. Two companies that trade with each other, share a brand or have overlapping management are not affiliates for this purpose unless the ownership supports it. The documentary set usually includes certificates of incorporation, current share registers, share certificates, and any purchase agreement that created the relationship. Where a holding company sits between the two, the chain must be documented at every level. Evidence that both entities are doing business is separate and equally necessary: financial statements, tax filings, payroll summaries and customer invoices show regular activity in a way that a lease and a telephone number do not.
Collect incorporation records, share ledgers, tax filings and the employment evidence as separate folders, then reconcile the dates across them. Hypothetical example: A linen-supply group acquired its U.S. affiliate through a holding company last year. The deciding record is the complete ownership chain on the filing date, not a slide deck calling the businesses affiliates. Missing intermediate share records can make a genuine relationship difficult to prove.
The final package should enable a reviewer to follow ownership without inference. Label each entity, country, owner and effective date consistently across the records.