I have a basement stairwell with 3-way switches (at the top and bottom of the stairs) and a light at the bottom of the stairs.
Each switch only has a single 12-3 Romex cable, and the light has two 12-2 Romex cables. (I'm not sure where power is entering the equation, or how each component is connected to the others). There must also be another junction box where one or more of these lead to.
My goal is to add a wall sconce at the top of the stairs, somehow connected off of "Switch B". Is this possible?