How to give objects of same type different setup configurations?

For simplicity's sake, say I have a Object Manager class A that manages resources between objects derived from same class class Bs.

A requirements are these:

1) Should have an instance of only one B at a time, we'll make that current B

2) Should remember the name or enum representation of the previous B so it can recreate when that B needs to be the current B again.

3) A has resources a, b, c, d

4) A is responsible for giving the current B only the resources the current B requires when it becomes the current B

the current implementation is like this. I'm hoping there is a better way since all the static_cast are annoying me.

class B
{
 public:
   void show()
 }

class Recording : public B
{
}

class Camera : public B
{
} 

class A
{
 a a;
 b b;
 c c;
 d d;

 enum Benum
  {
    Recording,
    Camera,
    InputSource,
    COUNT,
  }
 map<Benum, unique_ptr<B> Bmap;
 B* currentB;
public:

  void init()
  { 
    Bmap[Benum::Recording] = make_uniqe ...
    Bmap[Benum::Camera] = make_uniqe ...
    ...
  }

  switchB(Benum b)
  {
  switch(b)
  {
  case Benum::REcording
    auto recording = static_cast<Recording>(Bmap[Benum::Recording].get());
    recording->setup(a, b, c)
    currentB = recording;
  case Benum::Camera
    auto camera = static_cast<CAmera>(Bmap[Benum::Camera].get());
    camera->setup(b, c)
    currentB = camera;

  currentB->show();

This works fine, but just for engineering challenge, is there a better way to do this? To me this seems like a code smell. Reading this, I have to understand that the enum represents the objects. If the enum ever changes the whole class would have to be touched. It just doesn't seem easy to maintain.