A purchase agreement with a price allocation, an escrow agreement releasing funds on visa issuance, the seller note with its security terms, the home line-of-credit agreement, and statements tracing each dollar from source to closing. Ambiguity in the note is the usual problem.
Make the money legible from the first page
The officer will reconstruct the deal from the paper, so the paper should make reconstruction easy. The purchase agreement should state the total price and allocate it between equipment, goodwill, inventory and real property or lease. The escrow agreement should hold the couple's cash with release conditioned only on E-2 issuance, which makes the funds irrevocably committed while protecting them if the visa is refused.
The promissory note should state the principal, the term and, above all, the collateral; if the security is the car wash, that is the amount excluded. The line-of-credit agreement should show the couple as borrowers and the Saskatchewan house as security. Bank statements should show savings accumulating from declared income, the credit advance arriving, and both moving to escrow.
Add the business's last three years of financial statements and its current payroll register. A one-page schedule reconciling every source to every use, prepared by the couple's accountant, saves the officer from doing the arithmetic.