Two base classes can communicate

class base
{
public:
    base() { }
    ~base() { }
    virtual void saida() { cout << "base" << endl; }
};

class extra : public base
{
public:
    extra() { }
    ~extra() { }
    void saida() { cout << "extra" << endl; }
};

class derivada : public extra
{
public:
    derivada() { }
    ~derivada() { }
};


int main() {

    base* b = new derivada;

    b->saida();

    return 0;
}