The original fog lights remains the original fog light.
As soon as you turn on the fog light, the extra positioning light goes off and the original fog light burns at full strenght.
It is a simple wiring.
I installed the same light bulb (21W) in the non used fog light.
When turning on the lights, this second lamp comes in series with the original fog light, resulting in an output of about 5W each, since they only get 6V each. ( half the voltage result in 1/4 of wattage).
The most difficult part is to make the hole to fit an extra bulb connector.
You have to make the same hole as the original fog light, buy a second fog light holder and connect between red wire of licese plate light and original fog light yellow wire.
I have done this while I was installing the backup camera so I had access to all the wires...
If you realy want to do this and you know nothing about removing pannels, drilling holes, wiring ... ask a friend who can ( or visit me in Belgium ha
)