Collect the signed loan agreement, the security instrument as registered, every amendment, the lender's disbursement advice, and statements showing the funds arriving and leaving each account. Document any down payment as well, if the arrangement includes one. Unsigned drafts and email summaries do not substitute for executed instruments, and a gap in the trail invites questions.
Executed instruments, disbursement advices and the amendment trail
Where prescribed historical tax records are requested, produce them rather than arguing that they are old. If a government notice or a lender statement contradicts your own records, investigate the conflict and document it instead of repeating information you know to be wrong. Keep what the lender said in writing and what a representative said publicly or orally — such statements can be legally relevant later.
Order the documents by the date each was executed and mark which of them are registered, since a security instrument that has not been registered may not do what the parties assume. Where the lender issued a payout or disbursement advice, keep it with the account statement showing the money arriving, and note any difference in amount or date on the face of the record. If a family member contributed to a down payment, obtain that person's own source evidence rather than a letter describing it, because a description is not the thing described.
Where a document exists only in French, arrange the full English translation with the appropriate translator certification when you collect it, not when you file.