*has skimmed over the thread*
If you bring the 4 cables to the one box, if you crimp one of the new cables to one of the old in the back of the box, and put the remaining old and new pair in the socket terminals, thats acceptable, doubt you'll do it in anything less than a 35mm back box tho... (if you're careful you can do it with minimal distruption to the surrounding wall*)
*But there will be some
If you bring the 4 cables to the one box, if you crimp one of the new cables to one of the old in the back of the box, and put the remaining old and new pair in the socket terminals, thats acceptable, doubt you'll do it in anything less than a 35mm back box tho... (if you're careful you can do it with minimal distruption to the surrounding wall*)
*But there will be some
