Does anyone have any tips for precise alignment of adjacent metal back boxes in a solid plastered wall? I'm replacing 2 x 1 gang single boxes with a 2 gang box and a single gang box. I'd like to align the boxes so that there is no vertical gap between the installed sockets. They also need to align horizontally as well! Screwfix item code 60079 dual double/single box would be ideal except its for dry lining only. Item code 48234 is metal, but 2 x single only. Anyone tried using conduit fittings to align the 2 boxes with the required space in-between? Did it work? Any other suggestions for correct spacing (apart from use of spirit level and tape measure.....)?