Possible to do partial blending? f.e. Control how much blending?

For example, can we do something like THREE.AdditiveBlending, but just partially (like a certain percentage)?

Why not just using opacity?

https://jsfiddle.net/f2Lommf5/2567/

That affects the parts of the object that isn’t overlayed on the second object. Suppose two circles intersect partly, then blending will only affect the area that is shared. Opacity affects the area outside the shared area too, which I don’t want.

I guess it goes to say, I should probably put up an example.