Write from facts rather than momentum
Pause long enough to remove accusations, assumptions, and details that belong to someone else. For a message about how to put family loan terms in writing, use this factual base: list the amount, date, reason, receipt, prior agreement, and any part that remains genuinely disputed.
Offer a proportionate next step
Match the size of the request to the relationship and to what the recipient can reasonably decide now. Propose a payment, refund, evidence exchange, or installment plan with dates both sides can assess. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Protect privacy on both sides
Do not threaten public exposure, add invented fees, or treat hardship as proof of dishonesty. Use secure payment methods and qualified banking, consumer, legal, or fraud support when appropriate. Use the most private legitimate channel available and do not share the exchange to recruit support or pressure.