Sorry to gravedig, but I'm actually developing a timeline around this exact question, and I believe I have a passable point of divergence. This point of divergence revolves around the founding of the Independent Social Democratic Party of Germany (USPD), after antiwar revisionists grouped around Eduard Bernstein and antiwar centrists grouped around Karl Kautsky and Hugo Haase were purged from the SPD. In our timeline, these groups, along with the Spartacist League grouped around Rosa Luxemburg, founded the USPD on April 6, 1917.
The point of divergence is that, for whatever reason (polemics with groups such as the Bremen Left, inability to attend the conference due to sickness or accident, unwillingness of the centrists or the revisionists to include revolutionaries, etc.), the Spartacist League does not join the USPD. Instead, shut out of this party and probably critiquing it mercilessly due to being shut out, it regroups with the other left forces in Germany (the aforementioned Bremen Left, which included Pannekoeck, Gorter, and Radek; Eugen Levine's group in Munich; other, smaller, groups based in Berlin) to found the Communist Party of Germany (KPD) on June 24, 1917.
This means that the KPD exists a year and a half "early" (in OTL it was founded January 1, 1919), meaning that it, not the USPD, will attract the most militant workers coming out of the January Strikes, that the Revolutionary Stewards will ally with them instead of being put off by the Left's alliance with the Center as in OTL, and that the recruitment of Red Guards, particularly in Bavaria and Bremen, will begin in early November 1918, rather than in mid-December, giving them time to prepare for combat. It will also mean a more effective propaganda in the Berlin garrison, particularly in the People's Navy Division after the Christmas Crisis. Not incidentally, it will also mean that the German government, fearful of militant action at home, will act in a more temperate fashion during the Brest-Litovsk negotiations and in Finland, allowing the Bolsheviks to escape the negotiations with Latvia, Estonia, eastern Poland, and Ukraine formally theirs, and encouraging the Bolsheviks to intervene more boldly in the Finnish Civil War, leading to the victory of the Finnish Reds.
By the time the Versailles Treaty is ready to sign, the Communist government will be the only government with significant control over German territory. von Seeckt will have established a military dictatorship in east Prussia, Ebert and company will have fled to Freiburg, and Adenaur will have brought off a declaration of Rhenish independence. Versailles will reflect this, with Prussia, Swabia, and the Rhineland being granted independence, and with all the other clauses (reparations, loss of territory to Poland, Denmark, war guilt, etc.) in place.
You then have the Germans able to intervene in the Polish-Soviet War. They help the Soviets win, and claim the Corridor and Upper Silesia for themselves as spoils. Pilduski's National Front is fatally weakened, and the SDKPiL manages to bring off a revolution. Luxemburg and Radek travel to Poland to help bring this about, and remain there.
Italy's revolution begins in 1919 but matures in 1920, with Bordiga and the southern wing of the party able to compliment the council movement in Turin, Milan, Venice, and Florence with similar uprisings in Naples and Palermo. France provides military aid to the Pope, who reclaims the Patrimony of St. Peter. France and Britain also divide Italy's colonies, and France occupies Sardinia, but the rest of Italy falls to the communists.
Not quite what you wanted (I assume you were going for something more complete), but feasible given the PoD.