Two Different Voltages Same Wire

I drew up a schematic that shows location A and B which are 400 feet apart. I would like to run 12 volts DC in one direction and 120 volt AC in the other direction on the same wire, but not at the same time of course. The switch when on will hold the two relays closed allowing AC to flow from location B to location A when the switch is turned off both relays will open and connect the normally open contacts in both relays allowing the 12 volts from the battery to flow from location A to Location B. I added a fuse at battery in case. Will this setup work as it looks to me that it will work?

I'd go ahead and say no. I don't understand why you have the voltage sources in series with the relays' electromagnets. Why not just have the 12V battery power the two relays' electromagnets through an SPDT switch while the voltage sources are in series with only the relays' switches? Or if having the currents go through the same wire is mandatory, you could simply use just an SPDT switch alone. It'd have to be a pretty rugged switch if it'll be carrying a substantial amount of current, but it's extremely simple and extremely efficient.

I think this is basically what you intend. (Diagram attached.) (Test before implementation !)
(I am assuming you have sufficient knowledge to work safely on mains voltage equipment.)

Use 120 VAC powered relays.

The AC will hold the relays on, so the switch may be optional. The LEDs will come on automatically in the event of AC power failure. (Which I assume is your intention.)

Operation start:
Battery is supplying LED circuit.
When the AC mains comes on, Relay 1 disconnects the LEDs from the battery, the line becomes AC, Relay 2 disconnects the battery from the line.

A possible problem is that whilst the AC power is coming on, the battery will have the AC connected to it momentarily until Relay 2 changes over. However, because of the brief time, a car battery will not suffer from this.
(Hopefully, the AC and DC fuses will not blow in this brief time.) (Use slow blow fuses.)
(Anyone have ideas for improvement here ?)

When the AC drops out, if an inductive load such as a motor is connected to AC Out, the 15V Zeners protect the LEDs from momentary back EMF whilst Relay 2 is changing over.

(P.S. save diagrams as GIFs, not JPGs, then you can modify them without loss of sharpness.)

I can see that the relay 2 would have a short amount of AC applied to battery before AC relay switches. One could put a diode between fuse and relay this would stop half of the AC cycle as voltage drop thru diode would not matter..

Good idea, a diode in series with the battery fuse would help.

One could just use two sockets and plugs on each end of wire if one can get lamps, LEDs, neon to work on both ends with 120 VAC and 12 VDC on the same wire to indicate that there is 12 volts DC on AC power source end or on battery end that there is no AC voltage present to tell that it safe to connect to AC when other end is connected to 12 volt battery or visa versa.

The relays make operation automatic, but having a lamp each end to show when AC power is on is a good safety point.