I currently have a double switch at the top of the stairs which operates both up and downstairs lights and a single switch at the bottom of the stairs which only operates the downstairs light. I would like to replace this downstairs switch with a double that would also operate upstairs light. Does this mean that there has to be 2 pieces of 3 core and earth between the two switches?
![Confused :confused: :confused:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)