Secondary texture with Add Blending

[Thalenberghen]

I want to ask if there's a way to have a secondary texture with "Add" Blending. Most rfactor tracks use this quite heavily for adding details or something like that, so it would be cool to have it in KRP too. In the wiki I could only find Multiply Blending, but this makes it way darker if the original is Add, so I thought I'd ask how the other Converters solved this 
Thanks for any advice