Under which circumstance is formal documentation of a member's family care plan NOT required?

The correct choice indicates that formal documentation of a member's family care plan is not required for a single parent with custody of children over 19 years of age. This is based on the policies governing family care plans, which recognize that children who have reached adulthood (typically recognized at age 18 in many jurisdictions) no longer require the same level of care and supervision that younger children do.

In the context of military regulations, the family care plan is primarily designed to ensure that appropriate care is arranged for minor children when the service member is unable to provide that care due to deployment or other duties. Once children turn 19, they are generally considered adults and are capable of making their own decisions and managing their own care; thus, the need for a formal plan decreases significantly.

Other scenarios, such as having a single parent with custody of children under 18, married personnel without children, or personnel on deployment, involve circumstances where either the presence of dependents requires oversight or planning, or where a member's availability to care for their dependents may be impacted, necessitating a formal family care plan.