Use executed purchase, note, security, guarantee, escrow, closing, and banking records.
Build a dated transaction account
Collect the executed documents in the order they took effect, and let them override every summary. The core set is the asset or share purchase agreement with its schedules, the promissory note, the security agreement and any financing statement filed against company assets, the personal guarantee if one was given, the escrow instructions, the closing statement, and bank confirmations for each transfer. Add the bill of sale, the lease or lease assignment, and any licence or franchise consent, since those show a business that is real and able to trade.
Beside them, run the source-of-funds record: where the buyer's money came from, the tax filings or sale documents accounting for it lawfully, and a statement for every account it passed through on its way to the American operating account. Two habits save trouble later. Keep superseded drafts together with the amendment that replaced them, so a change in collateral or price is explained by the documents themselves.
And record the date each item took effect rather than the date it was scanned, because the account is read as a sequence, and a broker's one-page description of that sequence carries no weight against the signed instrument. Those exhibits exist to establish the elements themselves: treaty nationality for the investor and for at least half the enterprise's ownership; capital that is the investor's own, lawfully sourced, irrevocably committed and at risk; an amount substantial in proportion to the total cost of acquiring or creating this enterprise, since there is no universal minimum; a real and operating business that is more than marginal; and an investor who develops and directs it — in a temporary status that carries an intent to depart and opens no direct path to permanent residence.