How does the Family and Medical Leave Act (FMLA) define family members?

Spouse:
A husband or wife as defined under Tennessee law, or a marriage recognized as valid where it was entered into. This includes same-sex and common-law marriages that are legally recognized in at least one U.S. state.
Parent:
A biological, adoptive, step, or foster parent, or someone who stands in place of a parent (“in loco parentis”).
This includes a person with day-to-day care or financial responsibility for a child but does not include parents-in-law.
The FMLA Coordinator may ask for documentation confirming the family relationship, such as a birth certificate, court document, or written statement from the employee.
Son/Daughter:
A biological, adopted, foster, or stepchild, legal ward, or a child of someone standing in place of a parent who is:
•    Under age 18, or
•    Age 18 or older and incapable of self-care because of a mental or physical disability.
For children over 18, FMLA applies only if the child:
1.    Has a disability under the Americans with Disabilities Act (ADA),
2.    Cannot care for themselves,
3.    Has a serious health condition, and
4.    Needs care because of that condition.
For military caregiver leave, a “son or daughter” may be any age.
Next of Kin:
The service member’s closest blood relative, other than a spouse, parent, son, or daughter. Priority is:
1.    One designated relative in writing
2.    All relatives with legal custody
3.    Brothers and sisters
4.    Grandparents
5.    Aunts and uncles
6.    First cousins
For more information, visit the State of Tennessee Attendance and Leave Manual.