(1) Each individual health care service plan contract that is not grandfathered and that provides coverage for a subscriber's child must offer the option of covering any child under the age of twenty-six.
(2) Each group health care service plan contract that is not grandfathered and that provides coverage for a participating member's child must offer each participating member the option of covering any child under the age of twenty-six.
(3) Each grandfathered health care service plan that provides coverage for a subscriber's child must offer the option of covering any child under the age of twenty-six unless the child is eligible to enroll in an eligible health plan sponsored by the child's employer or the child's spouse's employer.
(4) As used in this section, "grandfathered" has the same meaning as "grandfathered health plan" in RCW
48.43.005.