Following Balistreri v. Balistreri (2022) 75 Cal.App.5th 511, this decision holds that if a trust provides a procedure or method for amending the trust, whether phrased as exclusive or optional, any amendment must conform to that procedure or method; otherwise it is invalid. Prob. Code 15402’s “qualification ‘[u]nless the trust instrument provides otherwise’ indicates that if any modification method is specified in the trust, that method must be used to amend the trust.