Except as provided in section 524.3-1201, to be effective to prove the transfer of any property, to nominate an executor or to exercise a power of appointment, a will must be declared to be valid by an order of informal probate by the registrar, or an adjudication of probate by the court in a formal proceeding or proceedings to determine descent, except that a duly executed and unrevoked will which has not been probated may be admitted as evidence of a devise if (1) no court proceeding concerning the succession or administration of the estate has occurred, and (2) either the devisee or the devisee’s successors and assigns possessed the property devised in accordance with the provisions of the will, or the property devised was not possessed or claimed by anyone by virtue of the decedent‘s title during the time period for testacy proceedings.