Well, Marc, this is the story that I´ve found:
Anna Dorothea von Medem, aged eighteen, marry Peter von Biron duke of Curland, aged fifty five and twice divorced. Anna Dorothea was a sweet and delightful creature, but the husband was an angry and fierous man. They had not a succesful marriage. Anna Dorothea fulfilled her duty giving birth to five daughters and a son. It´s possible that the last of her daughters, Dorothée, was fathered by her lover Alexander Batowski. When Peter and Anna Dorothea ended their marriage, Peter established himself with his daughters Wilhelmine (his favourite), Pauline, Johanna and Charlotte at Sagan. By the way, Anna Dorothea was sometimes at Löbichau and sometimes at Berlin, always with her younger daughter Dorothée and, also, with Alexander Batowski.
Alexander Batowski was not the only lover of the beautiful Anna Dorothea. She had a "liaison" with the count Pahlen, and, later, when she was the rich widow of Peter Biron, she was involved with the baron of Armfeld, a noble exiled from Sweden. After the death of Peter, the four elder daughters were taken to Karsbad with their mother and their sister (maybe half-sister) Dorothée. Baron of Armfeld mannaged the situation to find good matchs for them.
About Wilhelmine
Anna Dorothea and Armfeld tried to marry Wilhelmine with prince Louis Ferdinand of Prussia. They had all the support from princess Louise of Prussia, married to a prince Radziwill: Louise, sister of Louis Ferdinand, was a close friend of Anna Dorothea and also godmother of her younger daughter Dorothée. But at Berlin there were a lot of people who thought that the daughter of the last duke of Courland was not a suitable bride for a Hohenzollern prince. Berlin rejected the idea of this marriage.
By this time, it is said that the handsome baron Armfeld had seduced Wilhelmine and Anna Dorothea knew so well that her daughter was pregnant. So, they hurried Wilhelmine to marry Louis de Rohan-Guéméne. A few months later, Wilhelmine gave birth to the daughter fathered by Armfeld, Gustava, nicknamed Wawa, who was send to Sweden.
In 1805, Wilhelmine, still the mistress of Armfeld, divorced Louis de Rohan. She married secondly a russian prince, Troubeskoi, but in 1806, Wilhelmine was divorced again. At this time, two of the sisters of Wilhelmine, Pauline and Johanna, had also separate lives from their husbands, a prince Hohenzollern and a prince of Arenza. And at this time, 1806, the younger sister Dorothée was engaged to Alexandre Edmond de Talleyrand-Périgord, duke of Dino, a nephew of Charles Maurice Talleyrand; the couple was married in 1809 at Francfort.
During the napoleonic era, Wilhelmine was the mistress of prince Alfred von Windischgratz and, in 1810, she met Clemens Metternich. The personal assistant of Metternich, Gentz, was the lover of Johanna, sister of Wilhelmine; and Wilhelmine, herself, became the lover of Metternich. It was a funny situation, because two mistress of Metternich, Wilhelmine and the russian princess Ekaterina Bragation, shared the same palace, Palm, during the Congress; she hated each other fiercely, and all the people gossiped about the triangle. At the Congress, Wilhelmine was named the Cleopatra of Courland, and Ekaterina Bragation was named the Russian Andromeda. The younger sister of Wilhelmine, Dorothée, was also a main figure at the Congress, due to the fact that she was the mistress of Charles Maurice Talleyrand, the uncle of her husband.
She had another romances when she ended her relationship with Metternich: first, she was the mistress of Charles Steward; later, she shared seven years of her life with Wilhelm Lichnowsky.
