Hello!

I bought the regular edition of Heretek, but would like to upgrade to the + version to support the developers.
Is there any way to do that please?

Same wish for me, for both the vanilla version and the DLC. (those musics are so good)

Ce jeu est arrivé de façon relativement inattendue et c'est une belle surprise présentant un beau panel d'éléments superbement travaillés. (gameplay, cohérence de l'univers, design sonore, musiques, pirouettes avec le canon W40K...)

Des upgrades de versions seraient bienvenues.

I'm wondering the same for the base game. I bought the cheaper version because this is the first turn based game I've ever bought (if we exclude Worms) and I wasn't sure if I'll like it or not. Turns out I really like it.

I want upgrade base game and DLC to Omnissiah and Heretek+ editions too, like on Steam. Those soundtracks are awesome!

Same. You can on steam :(

I just didn't see that there were two separate editions. I added the DLC to my cart from the Omnissiah Edition page and it didn't show me that there was a separate edition of the DLC.

While I knew there were separate editions, what I didn't know is how much I'd enjoy the game and want to support this studio. If an upgrade option existed on GOG I'd happily purchase it.

The only way to do it is to request a refund, they'll refund the product and give you GOG credit so you can upgrade if you wish.
It's a pain, but I'm fine with it.