Surely the fog lights connection is straight onto the back of the bulbs? been 5 years since i put new fogs on.
The dash switch throws the heavier relay switch and with the relay switch live the front fog warning light comes on also. This sends a live feed through the fuse 4 to the fogs (grey wire) which passes through a line connector which splits the feed to both fogs. That connector is near the right hand fog, drivers side. You may have to take the fog back out to trace/find it the first time but can get to it from under the bumper once you found it. Failing that the only thing left is the black earth wire.