For a multi party account, are all parties required to sign the Account Selection Form or is it acceptable for any one of the parties to sign?

We are going to a new forms provider and the way they present the form is different than how we have previously done it. A blank general version of the form, with the acknowledgement, is provided first. One party will initial their selection and sign that form under the acknowledgement. A second version, without the acknowledgement or separate signature, is included on the signature card that the customer will initial next to their selection.

We currently require all parties to sign the acknowledgement. The new proposed version only has space for one party to sign. Do you know if this is acceptable.

Thank you!