Remember how SD's mother, Sophia Dorothea of Celle [henceforth SDC], was locked up by G1 for consorting with her lover? I was reading this episode in Horowski, cross-checking in Wikipedia, and found the following:
When his affair with Sophia Dorothea threatened to become public, von Königsmarck handed their love letters to his brother-in-law, the Swedish Count Carl Gustav von Löwenhaupt. The latter's heirs later offered the correspondence to the House of Hanover for money but they demanded such a high price that the court rebuffed them and questioned the authenticity of the letters. The correspondence was published in the middle of the 19th century and the majority of the letters are now in the possession of Lund University in Sweden. A few of the letters ended up in the possession of Sophia Dorothea's grandson, King Frederick the Great of Prussia, after his sister, Swedish Queen consort Louisa Ulrika, allegedly stole them and sent them to him. Today the authenticity of the letters has been established beyond any doubt.
So apparently Heinrich gets letters written by Grandma Sophia Charlotte, and Fritz gets (stolen!) letters written by Grandma SDC!
Sophia Dorothea of Celle
When his affair with Sophia Dorothea threatened to become public, von Königsmarck handed their love letters to his brother-in-law, the Swedish Count Carl Gustav von Löwenhaupt. The latter's heirs later offered the correspondence to the House of Hanover for money but they demanded such a high price that the court rebuffed them and questioned the authenticity of the letters. The correspondence was published in the middle of the 19th century and the majority of the letters are now in the possession of Lund University in Sweden. A few of the letters ended up in the possession of Sophia Dorothea's grandson, King Frederick the Great of Prussia, after his sister, Swedish Queen consort Louisa Ulrika, allegedly stole them and sent them to him. Today the authenticity of the letters has been established beyond any doubt.
So apparently Heinrich gets letters written by Grandma Sophia Charlotte, and Fritz gets (stolen!) letters written by Grandma SDC!
The source for this is Friedrich der Große: Gedanken und Erinnerungen. Werke, Briefe, Gespräche, Gedichte, Erlasse, Berichte und Anekdoten. Stabi link for when Stabi is a thing again. I'm willing to buy this for our library if it has good stuff that's new to us, but not sight unseen.