27 Miss. Code. R. 220-I-1.3
"Beneficiary" means the person, persons, or trust designated by a Participant on a form prescribed by the Board to receive any benefit payable upon the Participant's death, or if none, the Participant's estate. The Participant may designate more than one Beneficiary or primary and secondary Beneficiaries, or may change the designation of a Beneficiary. If two or more, or less than all, designated Beneficiaries survive the Participant, payments shall be made equally to all such Beneficiaries, unless otherwise provided on the form designating such beneficiary. Elections made by a Participant in his beneficiary designation form shall be binding on any such Beneficiary or Beneficiaries. A Beneficiary may, after the death of the member, designate his own Beneficiary. If none are designated by the Beneficiary, then his estate will be deemed the Beneficiary. Any beneficiary designation form must be received by the Third Party Administrator prior to the Participant's or Beneficiary's death.
27 Miss. Code. R. 220-I-1.3