I've toyed with this idea and I don't know if it's practical.
Neither RF nor power transmission is my area of expertise, so
forgive me if I am asking stupid questions.

Suppose I have a situation where I want to send power and control
signals to a device. Suppose too that I want to do this all with
2 wires (power and return). Is it at all feasible to send the data
on top of the power line, and have it separated at the destination?

Kinda like X10 but this is DC.

Any other ideas along these lines?

Michael