Possibly no longer relevant, but while looking up some tidbits from Lehndorff again, I came across an entry on November 16th 1753 where (after reporting that AW and Heinrich have started their RPG) he mentions he‘s just read a „History of our last four Kings“ by Pöllnitz. (Because it covers „four“ , he can’t mean one of the earlier memoirs.) (Though I assume Pöllnitz updated after the Seven Years War.) This is also only four days after Wilhelmine and the Margrave leave Berlin after their visit, and Pöllnitz is mentioned as around, quipping and socializing throughout the entire visit. Lehndorff doesn‘t say whether he read a handwritten copy or a private print, but he gives as title „History of (our last) four kings“ (of the House of Brandenburg“, and he was by no means a close friend of Pöllnitz, so that book must have been available at the Prussian court if you wanted it, and possible beyond.