How to access member of a class of one branch of heirarchy using pointer of class from another branch?

              class A
              /     \
          class B1  class B2

All classes have only public members. Class A is publically inherited and contains virtual member functions and non-virtual member functions with default print(cout) statements, class B1 and class B2 has only non-virtual functions, with definition of the virtual functions from class A. I want to know how to access all members of B2 using pointer of B1, which casting could be used. For example,

B2 obj_b2;
B1* b1_ptr=&obj_b2;

// Using b1_ptr, access all members of obj_b2

If yes, then whether this can be extended further into more deep branches like:

              class A
              /     \
          class B1  class B2
            /   \     /   \
       class C1 ...  ...  ...

(Accessing members of class C1, etc. from second branch)

---

EDIT 1: Maybe this will help; this is the example that I have written:

#include<iostream>
using namespace std;
class A{
public:
    virtual void v_f1(){
        cout<<"virtual A::v_f1()\n";
    }
    void f1(){
        cout<<"A::f1()\n";
    }
};
class B1 : public A{
public:
    virtual void v_f2(){
        cout<<"virtual B1::v_f2()\n";
    }
    void v_f1(){
        cout<<"A<-B1::v_f1()\n";
    }
    void f2(){
        cout<<"B1::f2()\n";
    }
};
class C1 : public B1{
public:
    void v_f2(){
        cout<<"B1<-C1::v_f2()\n";
    }
    void f3(){
        cout<<"C1::f3()\n";
    }
};
class D : public C1{
public:
    void f4(){
        cout<<"D::f4()\n";
    }
};
class B2 : public A{
public:
    void v_f(){
        cout<<"A<-B2::v_f()\n";
    }
    void f5(){
        cout<<"B2::f5()\n";
    }
};
class C2 : public B2{
public:
    void f6(){
        cout<<"C2::f6()\n";
    }
};
int main(){
    C2 c2_obj;
    C2* c2_obj_ref=&c2_obj;
    D* d_ptr = dynamic_cast<D*>(c2_obj_ref);

    // This statement gives segmentation fault,
    // if commented out, the code works fine.
    d_ptr->v_f();

    // These work fine
    d_ptr->f();
    dynamic_cast<C2*>(d_ptr)->f5();
    dynamic_cast<C2*>(d_ptr)->f6();
    return 0;
}