Charles Michael adopted his nephew Georg, Count of Carlow who was the morganatic son of his older brother Duke George Alexander of Mecklenburg (1859–1909) on 11 September 1928 and confirmed in the courts of Malchin on 5 October 1928.
Frederick Augustus' reign began on 13 June 1900, when his father died. His reign came to an end on 11 November 1918 , shortly before the German monarchy was abolished on 28 November 1918. Frederick was forced to abdicate his throne at the end of World War I , when the former Grand Duchy of the German Empire joined the post-war German Republic. 
Prince Frederick, Duke of York and Albany KG GCB GCH (Frederick Augustus; 16 August 1763 – 5 January 1827) was the second son of George III, King of the United Kingdom and Hanover, and his consort Charlotte of Mecklenburg-Strelitz. A soldier by profession, from 1764 to 1803 he was Prince-Bishop of Osnabrück in the Holy Roman Empire.
Though Duke Ernest fathered numerous children in various affairs, the two boys would have no other legitimate siblings. In 1826, their father succeeded as Ernest I, Duke of Saxe-Coburg and Gotha through an exchange of territories after the death of the duke's uncle, Frederick IV, Duke of Saxe-Gotha-Altenburg .
George III (George William ... St James's Palace, the King married Princess Charlotte of Mecklenburg-Strelitz, ... Ernest Augustus, Duke of Brunswick
The future George VI was born at York Cottage, on the Sandringham Estate in Norfolk, during the reign of his great-grandmother Queen Victoria. His father was Prince George, Duke of York (later King George V), the second and only surviving son of the Prince and Princess of Wales (later King Edward VII and Queen Alexandra).
19/11/2022 · Charlotte of Mecklenburg-Strelitz, ... Prince George, Duke of York, ... Ernest Augustus, Duke of Cumberland and Teviotdale