Maria Carolina was Queen of Naples and Sicily as the wife of King Ferdinand IV and III, who later became King of the Two Sicilies. As de facto ruler of her husband's kingdoms, Maria Carolina oversaw the promulgation of many reforms, including the revocation of the ban on Freemasonry, the enlargement of the navy under her favorite, Sir John Acton, and the expulsion of Spanish influence. She was a proponent of enlightened absolutism until the advent of the French Revolution, when, in order to prevent its ideas gaining currency, she made Naples a police state.

Maria Amalia was duchess of Parma, Piacenza and Guastalla by marriage to Ferdinand I, Duke of Parma. She was born an archduchess of Austria as the daughter of Empress Maria Theresa and Emperor Francis I.