Can you post a schematic of what you are trying to do
I think you are going to have to do a few short jumpers for your ground between lights. Which wouldn't be part of the harness.
Let's say i want to make 2 harness of for left side and other for right side. But I want one cable per each harness I said before.
The left harness to start, needs to ground 3 lights, lets say it has a red light which i want to power 2 ligths for brakes, other blue wire to power the same 2 lights for tail ligths and i have the other light want to be back up light with a brown color wire.
But i cant make the harness because the routing, edit wire can just make one point to other point.