Ertaan75: Strange...I chose the FC edition because the free DLCs, so it is not clear for me now how it works then.
Somebody (from GOG maybe) should clarify this question.
The Stellaris Dome set was originally a bonus DLC for people who pre-ordered Surviving Mars (any of the versions). They later made it available to purchase (on steam) for people who bought Surviving Mars after game launch, and after a couple of months on GoG for purchase.
If it became one of the DLCs included in the First Colony set, it would mean that the people who earned it as a pre-order bonus didn't actually
get a pre-order bonus - it would be counted instead as one of their 2 DLCs, but it was one that they should have had access to for free.
So...it's a separate pack. If you pre-ordered any edition of the game, it's a pack you got for free. If not, you have the option to purchase it.
(Note: I'm not from GoG, but I've read about what happened through the Paradox forums, and was one of the people who contacted Paradox after it was released on Steam to request a similar release on GoG - especially as GoG already
had the file due to it having been a pre-order bonus).