Sentence correction please

By this contract, John Doe agree to make payment to Sarah Mia, hereafter known as “Lenders” due to funds spent for extension of separate living quarters at STREET NAME, AREA NAME. This payment is enforceable by law and the method described below will be used in case of non-payment.

By this agreement, it is agreed that the payment of $xx will be surrendered to the Lenders once the payment for the sale of "Name and number if street" had been cleared.