(1) "Child" means a biological, adopted, or foster child, a stepchild, a legal ward, or a child of a person standing in loco parentis who is: (a) Under eighteen years of age; or (b) eighteen years of age or older and incapable of self-care because of a mental or physical disability.

As you can see from the definition, the term includes adult children who are incapable of caring for themselves due to a physical disability. The statute places no other limitation on the term or its coverage. Accordingly, so long as the child cannot care for him/herself due to a physical disability, the leave is available to the parent, regardless whether the adult child has a spouse or someone else who could provide care. See RCW 49.12.270.

Could a city or county be required to grant leave to an employee so that the employee could care for an adult daughter-in-law? No. As you can see from the above definition of "child," the relationship between the employee and the child must be either biological or the child must be adopted, a foster child, a stepchild, or a legal ward. This would not include a daughter-in-law.

Here is a question and answer from the Department of Labor and Industries concerning the family care law that further supports these conclusions:

7. Under what circumstances is a parent of an adult son or daughter covered? The scope of the rules includes children regardless of age, school attendance or marital status. If an adult son or daughter (i.e., 18 years of age or older) is “incapable of self-care because of a mental or physical disability … that limits one or more activities of daily living,” then s/he is covered under this rule. The disability does not need to be a chronic condition to be covered. Traumatic injuries, surgery, illness, and some conditions relating to pregnancy may also cause a temporary disability for an individual. A disabling condition is one that prevents an individual from engaging in activities such as bathing, dressing, eating, cooking, shopping, or using public transportation without active assistance. Some individuals with a mental disability would be even more limited for other basic needs described in the rules.

The answer appears to be yes, the city may designate the leave as FMLA leave. This conclusion is based on 29 C.F.R. 825.208, which states in part:

In all circumstances, it is the employer's responsibility to designate leave, paid or unpaid, as FMLA-qualifying, and to give notice of the designation to the employee as provided in this section.

This is a long regulation, but it is clear from reading it that, if an employee wants to take leave for something that qualifies as FMLA leave, the employer may designate it as FMLA leave, even if the employee wants it designated as sick leave. Sections (c) and (d) makes this fairly clear:

(c) If the employer requires paid leave to be substituted for unpaid leave, or that paid leave taken under an existing leave plan be counted as FMLA leave, this decision must be made by the employer within two business days of the time the employee gives notice of the need for leave, or, where the employer does not initially have sufficient information to make a determination, when the employer determines that the leave qualifies as FMLA leave if this happens later. The employer's designation must be made before the leave starts, unless the employer does not have sufficient information as to the employee's reason for taking the leave until after the leave commenced. If the employer has the requisite knowledge to make a determination that the paid leave is for an FMLA reason at the time the employee either gives notice of the need for leave or commences leave and fails to designate the leave as FMLA leave (and so notify the employee in accordance with paragraph (b)), the employer may not designate leave as FMLA leave retroactively, and may designate only prospectively as of the date of notification to the employee of the designation. In such circumstances, the employee is subject to the full protections of the Act, but none of the absence preceding the notice to the employee of the designation may be counted against the employee's 12-week FMLA leave entitlement. (d) If the employer learns that leave is for an FMLA purpose after leave has begun, such as when an employee gives notice of the need for an extension of the paid leave with unpaid FMLA leave, the entire or some portion of the paid leave period may be retroactively counted as FMLA leave, to the extent that the leave period qualified as FMLA leave. For example, an employee is granted two weeks paid vacation leave for a skiing trip. In mid-week of the second week, the employee contacts the employer for an extension of leave as unpaid leave and advises that at the beginning of the second week of paid vacation leave the employee suffered a severe accident requiring hospitalization. The employer may notify the employee that both the extension and the second week of paid vacation leave (from the date of the injury) is designated as FMLA leave. On the other hand, when the employee takes sick leave that turns into a serious health condition (e.g., bronchitis that turns into bronchial pneumonia) and the employee gives notice of the need for an extension of leave, the entire period of the serious health condition may be counted as FMLA leave.

The Washington Family Leave Act (ch. 49.78 RCW), requires employers to allow employees to use accrued sick leave, but only applies to employers with 50 or more employees at the work site (this applies to both state and local government employers). Washington law requires that all employers who provide any form of parental leave (other than maternity disability leave) to biological parents, must also provide this same leave for both adoptive parents and stepparents, and to men as well as women. The Act grants employees unpaid leave to be used to, among  other things, care for newborn or newly adopted children.  Note that employers must consult both the FMLA and state regulations and apply the most generous provisions.

When calculating the number of employees, the city must include part-time employees, seasonal or temporary employees, employees on leave, and employees that are shared with other jurisdictions. An otherwise eligible employee could qualify for leave under the FMLA if, on the day he or she applies for the leave, the city has more than 50 employees counted as explained above.

An employee may be on a workers' compensation absence due to an on-the-job injury or illness which also qualifies as a serious health condition under FMLA. The workers' compensation absence and FMLA leave may run concurrently (subject to proper notice and designation by the employer).

For more information, see our Family Medical Leave Act Web page.

[T]he legislature declares that it is the public policy of this state to require that employers who grant leave to their employees to care for a newborn child make the same leave available upon the same terms for adoptive parents and stepparents, men and women.

And, RCW 49.12.360(2) implements that policy by providing that “An employer must grant the same [parental] leave upon the same terms for men as it does for women.”