Hello

I cannot find any information on how to connect trailer socket to XC90 2005.
Trailer module is needed for vehicles manufactured since 2005 (I have checked that with my dealer). So I bought the trailer module but I don't know how to connect it. It is a typical trailer module similar to this one:

http://proteccss.pl/wp-content/uploads/2012/01/U2.pdf

I understand that it is necessary to connect each wire with the appropriate wire going to the rear lamps. E.g. direction indicators wires (3, 4) to car indicator wires, stop lamp wire (8) to car stop lamp wire and so on. I don't know how to connect the module fog lamps wire (9, 10) though. It is necessary to cut the fog light wire and connect it to the module, so that when the trailer is connected the car fog lamps is switched off, and the trailer fog lamps are switched on.
There are 2 fog lights in the XC90 (left, right), so should I cut both wires (and connect them to 10)?
I understand that it is not possible to use the REM trailer socket because the car would not know the trailer is connected so the fog lamps would be illuminated on both the car and the trailer, which is incorrect.
Please, anybody knows how to connect the tow bar socket to the XC90 2005?