(1)    The parties may agree in a consolidation agreement under s. 422.206 that the creditor may secure the consolidated obligation by a security interest in property in which the creditor has an existing security interest as a result of the prior transaction which is one of those agreed to become consolidated.

   (2)   For the purpose of determining the extent to which a consolidated obligation is secured after a consolidation of consumer sales, and after a consolidation of consumer loans in which one or more of the loans consolidated is secured by a purchase money security interest in property of the type described in s. 422.417 (3) (a), payments received by the creditor after a consolidation agreement are deemed to have been first applied to the payment of obligations arising from the transactions first made. To the extent that obligations are paid pursuant to this section, security interests in items of property terminate as the obligation originally incurred with respect to each item is paid.

   (3)   Payments received by the creditor upon an open-end credit plan are deemed, for the purpose of determining the amount of the unpaid balance secured by the various security interests, to have been applied first to the payment of finance charges in the order of their entry to the account, and then to the payment of the respective amounts financed in the order in which the entries to the account were made.

   (4)   If obligations consolidated or financed pursuant to an open-end credit plan arise from 2 or more transactions made on the same day, payments received by the creditor are deemed, for the purpose of determining the amount of the obligation secured by the various security interests, to have been applied first to the payment of the smallest obligation.