Yeah, I'm a little sketchy where OS2 is supposed to lie too, the only semi-quantitative measure I saw was "generations after OS1" on the KS. Depending on which races generations, that could mean some very different timescales. I took it to mean closer to OS1 than DD (otherwise DD would have been the nearest logical timeline landmark to compare it to), therefore somewhere after OS1 but before DD.
DD (actually, not even DD but Divinity 2) is closest to DOS2, because DOS2 comes after it. The Divine is dead, but his son Alexander is alive. Considering Alexander is not a Divine (but a mage who may be able to prolong his life) I'd say DOS2 comes 100-1000 years after DD. And I recall hearing 1000 years in one of the streams.
