After all we got a interessting discussion in my local GW supplying Store.
Teh Question appeared after to people tried to set up a game and one of them wanted to use the FW Heavy Gun Drones.
The other player argued he cant play the Drones cause Fw or no official rules distributed by GW.
The one with the Drones argued that the FW Rules are official cause FW is a part of GW.
My intention was that its polite to ask your opponent if you can use FW rules and to do without when the opponent says no.
So how do you handle it, or can someone give me a passage which clarifies this question.