Destroying and instantiating parent GameObject

Hallo everybody,

While building my game i've encountered a problem when i try to remove a parent game object (with all its children) and reinstantiating the prefab. Because the game objects already exist in my scene it seems as if i have to treat the already existing objects & the prefab objects as different objects. When i try to instantiate the prefab i have encountered numerous problems and i have tried numerous approaches to the problem. Some problems where that the instantiated prefab doesn't instantiate or that the Destroy function does not remove the objects. Anyway here is where i am at now.

     #pragma strict
 
 var letters : GameObject;
 var isDead = true;
 var allLetter : GameObject;
 var existingLetters : GameObject;
 
 function Respawn ()
 {     
        if(isDead)
        {
          Destroy(existingLetters);
          isDead = false;
          Debug.Log("i was here" + isDead);
          Instantiate(letters);
          allLetter = letters;
        } 
     
        if(isDead == false)
          {
         
                   Instantiate(letters);
                 
                 allLetter = letters;
                  
                Debug.Log("done this");
         
                Destroy(letters);
         
                Debug.Log("this");
          }
 
 
 }

The respawn function is called from another script. Is this because I'm trying to instantiate a parent object or am i failing big time code wise?

Thanks in advance.