An unbroken trail from where the money was earned to the account that pays the seller: business financial statements, tax filings, sale proceeds, account statements and any loan agreements.
The trail matters more than the total
An officer is asking two questions: was this money lawfully obtained, and is it the applicant's to risk. Answer the first with the history of the Ontario forestry business, its financial statements and tax filings, and documents for any asset sold to raise cash, including bills of sale and closing statements. Answer the second with account statements that follow the money continuously from those sources into the account used at closing, with no unexplained deposits and no gaps. Where funds were held jointly or came from a company, add the resolution or dividend record that moved them to the applicant. Where money was borrowed personally against an asset the couple owns outright, include the loan agreement and the security. Number the documents and provide a one-page schedule that maps each deposit to its source, because a reviewer who has to reconstruct the trail will ask questions instead.
Hypothetical example: a residential-glazing company owner funds the purchase with retained earnings from her Canadian corporation. The first review should trace the money from corporate profits through a properly authorized dividend or other lawful distribution into her personal account and then into the U.S. business. Financial statements, tax filings, corporate resolutions and bank records settle that chain. Do not skip the transfer step because the applicant controls the corporation; corporate assets are not automatically the individual's capital, and an unexplained jump between accounts invites scrutiny.