Final answer:
A receipt or proof of payment should be attached to the rental agreement once the wedding deposit transaction is completed to ensure evidence of payment and security of the rental.
Step-by-step explanation:
Once the wedding deposit transaction is completed, you should attach a receipt or proof of payment to the rental agreement. This serves as evidence that the deposit has been paid and secures the rental for the specified date and time of the wedding. Always ensure that the receipt includes the date of payment, the amount, and any other pertinent details that can identify the transaction specifically related to the wedding arrangements.