So make your 7 years war with alternative alliances, countries in it or results. Add a small timeline to it to demonstrate how your war goez
POD: 1759 following the Third treaty of Versailles (https://en.wikipedia.org/wiki/Treaty_of_Versailles_(1758)) and the Swedish intervention, Augustus III dies. France, Austria and Russia noting the thorough and utter ineptitude of the House of Saxony in both Saxony and Poland-Lithuania, support the 62 year old Count of Ourem (https://en.wikipedia.org/wiki/Infante_Manuel,_Count_of_Ourém) as their chosen candidate. Additionally, they motivate the Sejm upon his coronation to join the alliance declaring war on Brandenburg-Prussia.
The PLC, Austria, Russia and Sweden conclude the Treaty of Warsaw to not conclude a peace with Brandenburg-Prussia separately with the following war goals;
The Franco-British side of things continue as OTL, but things are worse for B-Prussia. The PLC launches a spirited campaign with their new allies, Sweden & the PLC co-ordinate and take Further Pomerania. Russia with better supply lines (and news supplies from the PLC itself + Austria) and Austria take Silesia in late 1759/1760. Joint armies of the four allies move and secure all of Neumark then march on Berlin, meanwhile news spread of Prussian defeats resulting in uprisings in Prussian-occupied parts of Saxony, Prussian forces withdraw. In the summer 1761, Berlin falls and Kottbus is occupied.
- The Kingdom of Prussia is to be returned to the PLC.
- Sweden would regain parts of Pomerania lost in 1720, and territories east of the Slupia/Stolpe river.
- PLC yields overlordship of Courland to Russia and this would be recognised by Sweden, Austria & the PLC. Prince Peter of Holstein-Gottorp is elected duke of Courland.
- Austria would gain Silesia and the Rhenish provinces of Brandenburg. The PLC would return Spiz to the Kingdom of Hungary (https://en.wikipedia.org/wiki/Treaty_of_Lubowla).
- Madgeburg & Cottbus would be separated from Brandenurg. Cottbus would be given to the Elector of Saxony, Madgeburg set up as a Free city under HRE administration or as seconditure (can't find/forgot how to spell the word, but I mean for the second son a la Austria and Tuscany) for the Saxon electorate to compensate for the loss of PLC.
- King Manuel of the PLC weds the 23 year old Maria Elisabeth of Saxony (https://en.wikipedia.org/wiki/Maria_Elisabeth_of_Saxony_(1736–1818))
The eastern bloc sends word to make peace with the broken Frederick as now former neutral states in the Empire begin sharpening their knives to knock him down a peg. The writing seemingly on the wall, the Eastern alliance makes puts forth offers for peace while still actively campaigning. Frederick is forced into battle at Postdam and captured. In the winter of 1761 (November) the eastern makes peace with the broken elector of brandenburg (The Great Icarus, his new sobriquet) in accordance with the Treaty of Warsaw. France accedes to the Treaty of Warsaw in exchange for monetary compensation from Prussia and removing all it's officers and troops from Anglo-Hanoverian service.
Austria moves to take possession of her newly acquired territories in the Rhine area continuing to allow French access via her territories to Hanover. Spain enters the War in 1762 in accordance to the Bourbon family compact, and we end with the same as situation in the wider world area between GBR & France.
Ivan VI is freed from captivity by the Russian nobility due to distate for Peter of Holstein-Gottorp, Ivan VI becomes a puppet Tsar to under the control of Vasily Dolgorukov-Krymsky (https://en.wikipedia.org/wiki/Vasily_Dolgorukov-Krymsky) marrying his daughter (https://www.geni.com/people/Евдокия-Васильевна-Грушецкая/6000000004391653320).
How realistic is it for the PLC to survive after the war?