'Life Events' section of the OPM website provides information useful to retirees and their families
There are many events in a retiree’s life that might affect your benefits, such as Marriage/Divorce, Name Change, Survivor Benefits, Reemployment, Designating Beneficiary, Rep Payee, Court Order, etc. OPM also publishes a pamphlet on Life Events the RI 38-126: Life Events and Your Retirement and Insurance Benefits (for Annuitants)(PDF file) pamphlet is available for download in the OPM Retirement and Insurance Publications directory.
Resource: Office of Personnel Management (OPM)