Section 32-3-107 - Contracts to make or revoke wills(a) A contract to make a will or devise, or not to revoke a will or devise, or to die intestate can be established only by:(1) Provisions of a will stating material provisions of the contract;(2) An express reference in a will to a contract and extrinsic evidence proving the terms of the contract; or(3) A writing signed by the decedent evidencing the contract.(b) The execution of a joint will or mutual wills does not create a presumption of a contract to make a will, or to refrain from revoking a will.Acts 1977, ch. 88, §§ 1, 2; 1978, ch. 745, § 1; T.C.A., § 32-308.