What does "Automatically expand league" affect exactly?
 

I'm trying to simulate MLB history staring in 1947 and want to control what teams relocate and when expansion happens. But I don't want to lose historical stadiums, park factors and historically accurate stats. Is there any way to make this possible in the settings? Or does turning off "automatically expand league" affect all these other features too? If the latter, is there a way to relatively easily update stadiums and park factors manually?