My house was built in 1926, hence, the switch boxes are all metal with conduit. There is an existing box, which houses a double switch and a single pole switch that operates 2 sconce light fixtures. My hope was to convert this metal beast to a 3 gang box and add a three way switch and another sconce light fixture, making the existing single pole double switch into a dimmer three way switch. does this make sense? anywho, I opened up the box and I am unsure where to start. I have some elementary wiring knowledge and many books, but none explain how to deal with expanding and existing metal box. I am thinking that because of the attached conduit, unless I intend to replace that with romex, it should be left in place. Is it ok to add an 'old work' single gang, plastic box next to the metal box? If so how would I knockout and mosy the wires over to the new plastic box? Someone with more knowledge, please advice. Even if its to say don't be a fool and pay an electrician a few hundred bucks. Thanks!