We recommend that OPM implement an eligibility verification process for family members to participate in the FEHBP by requiring marriage or birth certificates for all new enrollments. OPM should make it mandatory for federal agencies and/or insurance carriers to request proof of eligibility for family members to participate in the FEHBP, and the eligibility documentation should be maintained in accordance with records retention requirements. If OPM finds it unfeasible to have federal agencies and insurance carriers verify and maintain eligibility documentation for family members who participate in the FEHBP, it should consider contracting with a third party vendor to verify family member relationships.