A method according to any preceding claim, wherein the amount at any time due from the lender to the customer under residential purchase contract can be calculated as follows:

AmtDC2 = CVI*PP where:

AmtDC2 is the amount due under residential purchase contract at any time to the customer;

CVI is the lender's interest in the property expressed as a percentage; and

PP is the total purchase price that was paid by the customer.