This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
The rule that a modification in the contract or instrument which is made with the assent of the parties thereto, does not operate as an alteration, is limited to the parties who actually assent. If a modification is made with the consent of some of the parties to the contract, but without the consent of all of the parties thereto, the parties who do not consent may treat such written modification as an alteration; and if such alteration is material, they are discharged.1 An interlineation made after some of the parties have executed an instrument, and without their assent, renders it invalid as to them, although it is made with the assent of the remaining parties.2 The act of one of the makers of an instrument in changing its date, discharges other makers who do not assent thereto.3 If the addition of the name of a witness amounts to a material alteration,4 the addition of a witness with the consent of one of the obligors, discharges such instrument as to the obligors who did not consent thereto.1
14 Eadie v. Chambers, 172 Fed. 73, 24 L. R. A. (N.S.) 879 [reversed in Waskey v. Chambers, 224 U. S. 564, 56 L. ed. 885, on the theory that the deed, having but one witness and being altered after acknowledgment, was not entitled to registration].
15 See, also, discussion in Moelle v. Sherwood, 148 U. S. 21, 37 L. ed. 350.
16 Huffman v. Hatcher, 178 Ky. 8, L. R. A. 1918B, 484, 198 S. W. 236.
1 Dreyfuss v. Process Oil & Fuel Co., 142 La. 564, 77 So. 283; Shiffer v.
Mosier, 225 Pa. St. 552, 24 L. R. A. (N. S.) 1155, 74 Atl. 426; Barton Savings Bank & Trust Co. v. Stephenson, 87 Vt. 433, 51 L. R. A. (N.S.) 346, 89 Atl. 639.
See Sec. 3095 and Sec. 3121 et seq.
2 Dreyfuss v. Process Oil & Fuel Co., 142 La. 564, 77 So. 283.
3 Barton Savings Bank & Trust Co. v. Stephenson, 87 Vt. 433, 51 L. R. A. (N.S.) 346, 89 Atl. 639.
4 See Sec. 3098.
5 Sniffer v. Mosier, 225 Pa. St. 552, 24 L. R. A. (N.S.) 1155, 74 Atl. 426.