Schleswig-Holstein-Sonderburg-Plön-Rethwisch
The ducal line of Schleswig-Holstein-Sonderburg-Plön-Rethwisch descended from the line of Schleswig-Holstein-Sonderburg-Plön. It was founded by Joachim Ernest II (born 5 October 1637; died 5 October 1700) who as the third son of the Duke of Plön, Joachim Ernest, received the estate of Rethwisch in Stormarn as his inheritance.
Source: Wikipedia — Schleswig-Holstein-Sonderburg-Plön-Rethwisch (CC BY-SA 4.0)