Mo. Rev. Stat. § 461.042: Survival required.

1. An individual who is a beneficiary of a nonprobate transfer shall not be entitled to a transfer unless the individual survives the owner by one hundred twenty hours.

2. If an owner provides and the transferring entity accepts, or if a governing instrument or applicable law provides, a period of survival different than one hundred twenty hours, the period designated shall determine the survival requirement of beneficiaries under this section. An owner and transferring entity may agree that certain circumstances raise a different presumption of survival or nonsurvival.

3. This section does not apply to survivorship rights of joint owners.