I am trying to figure out if my exiting wiring will allow me to use a 3-way switch. I have 3-conductor wire going from a junction box to a dual-switch box. I would like to replace 1 of the existing switches with a three way switch. The other switch is wired to the same three way cable and passes power out to it's own light. The new 3-way switch would have to return the black and the red to the junction box and from there go out to yet another new 3-way switch and the light. This second new 3-way switch is not installed at all. No cable and no switch box even for it yet. Is this something I can do or do I need a dedicated 3-conductor wire for the 3-way switch in the dual switch box?