The official program terms as they read on the date of application, confirmation of the eligibility basis, records of the gift and processing fee paid through the official channel, and the applicant's identity, background and family documents. Keep a dated copy of everything, because terms can change.
A dated record of the terms you relied on
Begin with a saved copy of the official program page, the frequently asked questions and the executive order as they appeared on the day of application; if a term changes later, the applicant can show what was represented. Keep the application submission confirmation, the payment receipts for the gift and the processing fee showing the official recipient, and any correspondence from the program. Follow the I-140G and official instructions for identity, EB-1 or EB-2 eligibility, admissibility, and family documents; do not assume Canadian citizenship or veterinary credentials independently establish eligibility.
Because the gift is sourced from the practice sale, keep the sale agreement and bank records as the applicant's own payment trail, and supply source records if the official instructions request them. Do not rely on third-party portals to store these records, and never share payment details with an intermediary who claims to expedite the process.