You can't use 2 supplies for the same load.
You cannot entangle two supplies like this, it will create a death trap.
Aside from that, Mrs. Lincoln, the motion sensor will be a very unhappy puppy if its supply/load relationship is interrupted. Mainly, it will "forget" what the terrain looks like, tend to malfunction as a detector, while the light sensor that keeps it from coming on during the day will also forget what day and night look like. (Since that perspective varies depending on exposure and ambient light). Two better plans:
This is a cakewalk with a smart switches. You power the light off only one of them, the master. The other remote/slave smart switch has no wired connection to the light whatsoever. It uses radio waves or power-line signaling to communicate with the master smart switch. Shop carefully for products which do this.
Relay on one switch
Power the light from the motion sensor switch location. There, install a 12/24V relay with transformer (they make combo relay/transformers).
Use plain old low-voltage doorbell wire to connect the two switch locations, this is only carrying 12/24V so the rules are much relaxed. At the other switch location, install a surface-mount switch with no mains wiring in its junction box... and have that switch short the two doorbell wires. This operates the relay, whose contacts are wired in parallel with the motion sensor. If you wanted, you could use 3-4 wire doorbell/thermostat cable and put 12V motion sensors there.