It is a chain: an origin document for each source, statements showing the money in the account, records of every transfer and conversion, and a written narrative that ties them together with dates and amounts that reconcile.
Build the chain in the order the money moved
Start a spreadsheet before you start a folder. List each tranche of capital, its origin, the date it entered your control and every account it passed through. Then attach a document to each line. Business proceeds need the sale or distribution records and the company's own accounts; property proceeds need the sale agreement and the lawyer's or notary's statement; gifted funds need the donor's origin documents as well as the gift instrument. Foreign exchange steps need the conversion records. When the spreadsheet reconciles to the amount invested, the narrative writes itself. When it does not reconcile, you have found the problem while it is still fixable rather than in a request for more evidence months later.
Hypothetical example: Noel, a commercial-laundry owner, has a property-sale record but cannot link the proceeds to a later overseas transfer. He should reconstruct the chain with the original ownership evidence, closing statement, tax reporting, each bank statement and every transfer receipt through subscription. A final account balance proves possession, not lawful source and path. Project materials belong in a separate indexed section showing the applicable capital amount, the job-creation method and his management or policy role. Because residence begins conditionally, he should preserve both personal and project records for the later I-829 filing rather than assuming petition approval ends the evidence burden.