A family-plan management system integrating family plan widgets on mobile devices that interact with an API maintained and used by a central server is described. The family-plan management system enables high-visibility, low-effort communications between family-plan members as well as easy access to family-plan services offered by the central server. The API automatically identifies family plan members by accessing a database and then implements high-value web and mobile add-on services for the family plan members. The family-plan management system enables control and use of the family plan by the family plan member and enables the carrier to upgrade family plan services without direct action on the part of family plan members.