I seriously doubt this is possible via Python or even the C++ DLL. I expect that the fog of war is controlled by the core C++ game EXE, but I can't say I've verified this.
Okay, I'm not that positive about the C++ DLL part because you can change the visibility of terrain in world builder. Thus, it's possible from Python to alter the visibility. However, it's not Python that enables shared vision. That's done through C++ in either the DLL or EXE.