Mo. Rev. Stat. § 369.169: Minors, association may treat as an adult, when.

An association may issue an account to a minor as the sole and absolute owner and receive payments, pay withdrawals, accept pledges and act in any other manner with respect to such account on the order of the minor with like effect as if he were of full age and legal capacity. Any payment to or on the order of a minor shall be a discharge of the association to the extent thereof. The account shall be held for the exclusive right and benefit of the minor free from the control of all persons, except creditors.