AFAIK there is no difference between whether clear save data comes from a Steam version or from a GOG version. I don't see any reason why they wouldn't be interchangeable with each other.
Therefore, you probably should be able to do what you are trying to do, without having to re-buy the second game on Steam.
But with that said, I don't know why it isn't detecting your clear save data.
Are you 100% sure that there actually is clear save data stored on your machine? Because if there isn't, then that would explain why your copy of TOCS II isn't detecting any.
After you beat TOCS I, the game pops up a prompt that says something like "would you like to save the clear data?" If you said "no" to that, then the game wouldn't have created any clear save data, and hence in that case, there would be no file on your machine for TOCS II to detect & load.
In which case, if that's what happened, then the solution would be to reload your very final save game from TOCS I and beat it again, and this time choose the "yes" option when it asks if you want to save the clear data. Then after that, try to load up TOCS II again and see if it recognizes your clear save data.
Other than that, I'm not sure what might be causing your problems. Maybe someone else who knows more will post here as well.
Post edited March 18, 2021 by Ancient-Red-Dragon
