How did the SPD aim to integrate the old German upper classes into the new system?

The German Revolution or November Revolution (German: Novemberrevolution) was a civil conflict in the German Empire at the end of the First World War that resulted in the replacement of the German federal constitutional monarchy with a democratic parliamentary republic that later became known as the Weimar Republic. The revolutionary period lasted from November 1918 until the adoption of the Weimar Constitution in August 1919. Among the factors leading to the revolution were the extreme burdens suffered by the German population during the four years of war, the economic and psychological impacts of the German Empire's defeat by the Allies, and growing social tensions between the general population and the aristocratic and bourgeois elite. The first acts of the revolution were triggered by the policies of the Supreme Command (Oberste Heeresleitung) of the German Army and its lack of coordination with the Naval Command (Seekriegsleitung). In the face of defeat, the Naval Command  insisted  on trying to precipitate a climactic pitched battle with the British Royal Navy utilizing its naval order of 24 October 1918, but the battle never took place. Instead of obeying their orders to begin preparations to fight the British, German sailors led a revolt in the naval ports of Wilhelmshaven on 29 October 1918, followed by the Kiel mutiny in the first days of November. These disturbances spread the spirit of civil unrest across Germany and ultimately led to the proclamation of a republic to replace the  imperial  monarchy on 9 November 1918, two days before Armistice Day. Shortly thereafter, Emperor Wilhelm II fled the country and abdicated his throne. The revolutionaries, inspired by communist and socialist ideas, did not hand over power to Soviet-style councils as the Bolsheviks had done in Russia, because the leadership of the Social Democratic Party of Germany (SPD) opposed their creation. The SPD opted instead for a national assembly that would form the basis for a parliamentary system of government. Fearing an all-out civil war in Germany between militant workers and reactionary conservatives, the SPD did not plan to strip the old German upper classes completely of their power and privileges. Instead, it sought to peacefully integrate them into the new social democratic system. In this endeavour, SPD leftists sought an alliance with the German Supreme Command. This allowed the army and the Freikorps (nationalist militias) to act with enough autonomy to quell the communist Spartacist uprising of 5–12 January 1919 by force. The same alliance of political forces succeeded in suppressing leftist uprisings in other parts of Germany, with the result that the country was completely pacified by late 1919.