I wrote a little tool that let's you create an completely independent instance of your current EU4 installation including Mods and savegames so you can a) continue old campaigns after the DLC hit without having to revert your standard installation back and b) have all the mods for the old version available. This is completely independent from your main installation which you can then update to play with the new DLC/Patch and updated Mods.
https://forum.paradoxplaza.com/foru...reezer-save-current-eu4-installation.1052342/
https://forum.paradoxplaza.com/foru...reezer-save-current-eu4-installation.1052342/