Okla. Stat. tit. 6, § 6-910.3: Variation by agreement — When permitted

A. The effect of Sections 2 through 6, 8 through 11, and

Section 13 of this act may not be varied by agreement, except as

provided in those sections. Subject to subsection B of this

section, the effects of Sections 7, 12, and 13 of this act may be

varied by agreement.

B. A provision in an account agreement or other record that

substantially excuses liability or substantially limits remedies for

failure to perform an obligation under this act is not sufficient to

vary the effect of a provision of this act.

C. If a beneficiary is a party to an account agreement, the

bank and the depositor may amend the agreement without the consent

of the beneficiary only if the agreement expressly permits the

amendment.

D. If a beneficiary is not a party to an agreement and the bank

and the depositor know the beneficiary has knowledge of the

agreement’s terms, the bank and the depositor may amend the

agreement without the consent of the beneficiary only if the

amendment does not adversely and materially affect a payment right

of the beneficiary.

E. If a beneficiary is not a party to an account agreement and

the bank and the depositor do not know whether the beneficiary has

knowledge of the agreement’s terms, the bank and the depositor may

amend the agreement without the consent of the beneficiary only if

the amendment is made in good faith.