How does C ++ multiple inheritance work?

This question helped me sort out a little, but my question is slightly different from them.

Basic typecasting, as I understand it in C ++, involves reinterpreting a structure in memory as another structure. For instance:

class Building{int sqFootage;};

class Office : public Building{int cubicles;};

int main(int argc, char** argv){
    Office *foo = new Office();
    /*The cubicles member appears after the sqFootage member on an Office,
    * so the foo pointer is really just a Building* with some extra
    * information after it.
    */
    Building *bar = (Building*)foo;
    return 0;
};

The critical point here is that Office can be interpreted in memory as a building without any structural changes. This breaks down in case of multiple inheritance:

class Animal{bool alive;};

class WaterDweller : public Animal{float swimSpeed;};

class LandDweller : public Animal{float runSpeed;};

class Amphibian : public WaterDweller, public LandDweller{float transitionSpeed};

int main(int argc, char** argv){
    Amphibian *amph = new Amphibian();
    LandDweller *land = (LandDweller*)amph;
    WaterDweller *sea = (WaterDweller*)amph;
}

It is impossible to interpret amphboth a LandDwellerand a WaterDwellerwithout reorganizing the structure Amphibianin memory. How do these castes work, assuming they have some useful meaning? If not, is it possible static_cast, dynamic_castor reinterpret_cast?

EDIT: Sneftel. TinyDr, , , , c-, - , .

, , , :

land 0x22c8018
sea 0x22c8010
run 0x22c801c
swim 0x22c8014
land alive 0x22c8018
sea alive 0x22c8010

, , , , . , Sneftel .