Who married Maria Margarethe Prinzessin von Hohenzollern-Sigmaringen?

Carl Gregor Herzog zu Mecklenburg (14 March 1933 – 23 July 2018) was a German historian of music and art. He served as director of the Museum of the Roman Catholic Diocese of Rottenburg-Stuttgart for a period of 18 years, and was noted for his books on music and art. He was a member of the former Mecklenburg ducal family.