S.D. Codified Laws § 29A-6-108

Any financial institution may enter into multiple-party accounts to the same extent that they may enter into single-party accounts. Any multiple-party account may be paid, on request, to any one or more of the parties. No financial institution may be required to inquire as to the source of funds received for deposit to a multiple-party account or to inquire as to the proposed application of any sum withdrawn from an account for purposes of establishing net contributions.