Miss. Code Ann. § 63-21-255

(1) If a motor vehicle that is the subject of a beneficiary designation is owned by joint owners with right of survivorship, the beneficiary designation must be made by all of the joint owners. (2) A beneficiary designation made by joint owners with right of survivorship: (a) May be revoked or changed as provided by Section 63-21-261 , only if it is revoked or changed by all of the joint owners; and (b) May be revoked or changed by the last surviving joint owner as provided by Section 63-21-261 .