From the April 2022 handbook of instructions:
I’m trying to have an intelligent conversation with TBM in laws who work in the temple weekly but don’t seem to know their own rules.38.4.1.3
Sealing of Living Members after a Spouse’s Death
Women. If a husband and wife have been sealed and the husband dies, the woman may not be sealed to another man unless she receives a cancellation of the first sealing (see 38.4.1.4).
A living woman who is not currently married or sealed to another man may be sealed to a deceased husband. If the marriage ended in divorce, see 38.4.1.2.
A living woman who is currently married may not be sealed to a deceased husband without First Presidency approval.
See chapter 28 for information about performing ordinances for a deceased spouse.
Men. If a husband and wife have been sealed and the wife dies, the man may be sealed to another woman if she is not already sealed to another man. In this circumstance, the man does not need a seal- ing clearance from the First Presidency unless he was divorced from his previous wife before she died (see 38.4.1.2).
A living man may be sealed to a deceased wife. If the marriage ended in divorce, see 38.4.1.2. Before being sealed to a deceased wife, a man must receive written consent from his current wife if he is married.
See chapter 28 for information about performing ordinances for a deceased spouse.