Share registers, articles of incorporation and any holding-company or trust documents that show the ownership chain; financial statements, leases and invoices that show both businesses operate; and organizational charts that place the transferee in each structure.
Let the corporate records tell the story without narrative
USCIS decides the qualifying relationship from documents, so the petition should carry the actual share register of each company and, where a family holding company owns both, its register too. If the U.S. plant was bought rather than founded, include the purchase agreement and the closing date, because the qualifying year must be with a group member and the relationship must exist when the petition is filed.
Doing business means regular, systematic and continuous provision of goods or services; for a Boischatel precast business and its Maine plant, that is shown by production records, customer invoices, payroll for existing U.S. staff, and the plant lease or deed. Organizational charts should be dated and consistent with payroll.
For the transferee, provide the employment contract, T4s and pay stubs for the full qualifying year, a duty description written in terms of decisions and reports, and a résumé. Translate French documents and keep originals available.