Hi-Have two gang socket in kitchen which is part of the downstairs loop. The heating engineer took a connection of this to create a FSU for the heating. As a result there are three wires going into each of the terminals of the two gang. Was trying to get fourth wire into each for the wall unit downlighters but finding it really hard. Can I tap into the FSU for that or do you think that soldering all four so that they easily go into the respective terminals on the two gang. Hope this makes sense