(a) Subject to the power of the court to permit an amendment in the interest of justice:
(1) The third-party claim constitutes the pleading of the third person.
(2) In the case of a third-party claim by a secured party, the creditor’s statement constitutes the pleading of the creditor.
(b) A third-party claim of ownership, right to possession, or a lien, shall be deemed controverted by the creditor.