I have an existing switch that only controls one outlet. The switch is in a single gang box and has one white wire and one black wire connected to it, plus ground. No other wires are in the switch box. I believe based on this that the power source is at the outlet? I wish to add a second switch next this switch (making it a 2 gang box) to control recessed lighting. Is it possible to leave the original switch controlling the switched outlet but also to take power from the associated white and black wire for the new light switch? If not, what recommendations do you have?