I'm confused, are you saying you would want the blend to be lighter then light (255,255,255), or do you want it to wrap around back to black (0,0,0) and add up the leftover values from there?
If so, you could just do an if statement and check if said add value is above 255, then use mod to see by how many times you should subtract 255 from the answer no?
If so, you could just do an if statement and check if said add value is above 255, then use mod to see by how many times you should subtract 255 from the answer no?