proposals as creating new contracts. The summary judgment record does not present evidence that there were three separate one-year contracts, and Gallagher does not argue that in its brief. Therefore, Gallagher must demonstrate that it and the Diocese modified their contract to discharge Gallagher from the warranty. Under Louisiana law, contracts may be modified only by mutual consent of the parties to the contract. See Williams Eng’g, Inc. v. Goodyear, 480 So.2d 772, 778 (La.Ct.App.1985), aff'd, 496 So.2d 1012 (La.1986). In order to constitute a valid modification, an agreement must be clearly defined, and the party sought to be held to the modification must have in fact actually agreed to and authorized the modification. See Cardos v. Cristadoro, 228 La. 975, 84 So.2d 606, 610 (1955) (<HOLDING>); see also Wise v. Lapworth, 614 So.2d 728, 731
holding that no fiduciary duty existed between the plaintiff and defendant because there was no evidence that the parties agreed that defendant would be acting primarily for the benefit of the plaintiffs holding that an oral compromise and release agreement was unenforceable where there was no written stipulation between the parties holding that shareholder was liable under the law and contract because by the purchase of his stock he agreed and assented to liability as provided in the state constitution which was included in the articles of incorporation and thus created a contract on the part of the shareholders which followed them wherever they might go holding that there was no evidence that parties actually agreed to modify stock purchase agreement and thus contract was effective as originally written holding that plaintiff stated a claim for breach of contract when it alleged the government failed to purchase insurance for plaintiff as agreed by contract