Del. Code Ann. tit. 12, § 3342
(a) Unless the trust’s governing instrument expressly provides that the governing instrument may not be modified under this section, under a nonjudicial settlement agreement under § 3338 of this title or similar provision of law, or under a modification agreement, an irrevocable trust may be modified by the addition of a new provision or the modification of any existing provision—so long as such provision could have been included in the governing instrument of a trust were such trust created upon the date of the modification—by written consent or written nonobjection of all of the trust’s trustors, all then serving fiduciaries and all beneficiaries having an interest in the trust, regardless of whether the modification may violate a material purpose of the trust; provided, however, that unless the trustor, or a person acting on behalf of the trustor, confirms in writing that the transfer in trust is an incomplete gift for federal gift tax purposes, neither a trustor nor, on behalf of a trustor, a guardian or an agent under a power of attorney, may represent and bind any beneficiary (other than the trustor) with respect to the modification, notwithstanding any provision in the governing instrument, or applicable law, that provides that the trustor may represent or bind 1 or more beneficiaries. A trustor’s power to provide a written consent or written nonobjection to a trust’s modification may be exercised:
80 Del. Laws, c. 340, § 1; 81 Del. Laws, c. 149, § 1; 81 Del. Laws, c. 320, § 4; 82 Del. Laws, c. 52, § 1; 82 Del. Laws, c. 278, § 1; 83 Del. Laws, c. 69, § 2