how to make both work in simultaneous, when I apply a deactivates the other.
I have only in ReShade.fx:
#define VK_SPACE 0x20
#define ReShade_ToggleKey VK_SPACE
I'm a little unclear on what you're asking. Putting #include "GAUSS.fx" in ReShade.fx should be enough to get them working together. If you want to toggle GAUSS.fx you will have to change this line in GAUSS.fx,
technique t0 < enabled = true; >
to something like this,
technique t0 < enabled = true; toggle = 0x20; >
That will make them both use the same toggle key. If you want to use different keys to toggle them independently just change the number to match the key you want to use.
Hope that answers your question. If you need more help with it, start a new topic in the troubleshooting section.