Going to sound a bit bizarre but '''copy paste'' Confederacy is a thing that tends to show up in American timelines.
For the Union being pretty status quo with slavery on border states if they sided with the government in some cases till December 1865 if the USA is far more radical about the subjects these states will never think of joining the CSA, try and bargain for their support as they did in the OTL or be altered in any large ways despite arguably at the center of the conflict given their geography.
That's not saying they all joining would make the CSA win but rather would allow for a much longer and bloody war given they represented close to near 10% of the participants of the war, would explain the general decades long military occupation of the south that tends to happen if it was a near 100% clear break between slave and free states.
Instead seems the CSA will always form with the exact same strength, state and situation enough to guarantee no matter what happens in America.
For the Union being pretty status quo with slavery on border states if they sided with the government in some cases till December 1865 if the USA is far more radical about the subjects these states will never think of joining the CSA, try and bargain for their support as they did in the OTL or be altered in any large ways despite arguably at the center of the conflict given their geography.
That's not saying they all joining would make the CSA win but rather would allow for a much longer and bloody war given they represented close to near 10% of the participants of the war, would explain the general decades long military occupation of the south that tends to happen if it was a near 100% clear break between slave and free states.
Instead seems the CSA will always form with the exact same strength, state and situation enough to guarantee no matter what happens in America.