Combine rind and juices in a medium saucepan; add sugar, mixing well. Bring to a boil. Add butter and coconut; stir well, and boil 5 minutes.
Combine egg yolks and egg in a small bowl. Gradually stir in one-fourth of hot fruit mixture; add to remaining hot fruit mixture. Cook over medium heat, stirring constantly, 3 minutes or until thickened. Serve warm over ice cream or pound cake.
Note: Fruit sauce may be refrigerated in a covered container.