Notwithstanding subdivision (a)(1)(D), the formula referred to in subdivision (a)(1)(B) will be effective as to or deemed to convey and transfer to the decedent's spouse an unlimited sum, if the court having jurisdiction over decedent's probate estate determines in a proceeding in which all beneficiaries of the estate are represented, that based on all the facts and circumstances the decedent intended or would have intended that the formula should be applied so as to take advantage of the unlimited marital deduction allowed by federal law as amended by subsection (a) of § 403 of the Economic Recovery Tax Act of 1981. This subdivision (a)(3) shall apply only for decedents whose deaths occur after September 12, 1981, and prior to October 1, 1983, and, therefore, shall in no way affect the computation of the amount deductible for Tennessee inheritance tax purposes pursuant to §67-8-315(a)(6).