Non-dependent children can join FEHBP as of January 1st, 2011. The child doesn’t have to be your own. It can be your gay partner’s or someone else’s. If it is your own child, the child can be married and have their own employer-sponsored insurance. Almost any child living with a federal employee can be added. See the attachments from OPM. Some employees and retirees may overlook this important benefit change this Open Season.
OPM’s definition of “Foster Child” and “Step Child” is at
Changes for Federal Benefits Programs under the Affordable Care Act
Attachment: Health Reform Changes for Federal Benefits Programs Effective January 1, 2011