I'm sorry but I didn't answer you fully. Yes, the capitulation was done in the name of "His Exc. Mr. the count of Kleist, general of infantry, knight of the orders of the black-eagle and of the red-eagle, and of St. Alexandre et Neuski of Russia, military govenor of the town and citadel of Magdebourg." (loose translation) The actual accord however was negotiated through Major General von Renouard (chief of a regiment of infantry and knight of the order of military merit of Prussia), Colonel Dutrossel commandant of the military garrison, and Captain Leblanc of the Prince Louis of Prussia Regiment.
Which brings up another question? Marshal Ney is listed as being a Knight of the Order of Christ of Portugal...how did he get that?