More info needed! You do not describe how your fixtures are receiving their neutral connection. I don't understand why you
would ask if your new sconces may need additional wiring. How would they work if they had no wiring run to them? I also
don't understand why you describe the old wires/cable that ran from the switch box to the fan light. Presumably it would all be abandoned and
capped off. You can certainly use the bottom switch for controlling the sconces, provided proper wires are run. Is there knob-and-tube
wiring involved, or is it all in modern 2 and 3 conductor cable?