Update Hex Grid Cell After Shooting

i have arranged game object sphere in hex grid cell and some of the cell i have filled with empty transform.

When i shoot i am positioning my bullet sphere in empty position.. but next time when i shoot , my previous bullet disappears.

So how to arrange game object in grid so that it persist until i destroy.

Code to generate grid :

 public var sphere : Transform[];   
    private var B : int = 0; 
    private var G : int = 1;  
    private var P : int = 2; 
    private var R : int = 3; 
    private var Y : int = 4;  
    private var E : int = 5;   
    
    public var  m : int= 12;
    public var n : int = 12;
  
    public var radius : float = 0.5f;
    public var useAsInnerCircleRadius : boolean = true;
  
    private var go : GameObject;
    private  var offsetX : float;
    private var offsetY : float;
  
    private var formation  = [   [E ,E ,E ,E, E, E, B, Y, Y  ],
                                    [E ,E ,E ,E, E, E, Y, Y, Y  ],
                                  [E ,E ,E ,E, E, E, Y, G, G  ],
                                    [E ,E ,E ,E, E, E, P, R, G  ],
                                 [E ,E ,E ,E, E, E, R, R, R  ],
                                 [E ,E ,E ,E, E, E, R, R, R  ],
                                  [E ,E ,E ,E, E, E, P, B, B  ],
                                  [E ,E ,E ,E, E, E, B, Y, B  ],                                 
                                  [E ,E ,E ,E, E, E, G, E, Y  ] ];
                                          
    function Start() {
       CreateGrid();
       //StartAdjustments();
    }
  
 function HexOffset( x : int, y : int) : Vector2 
 {
       var position : Vector2 = Vector2.zero;
  
       if( y % 2 == 0 ) {
          position.x = x ;//* offsetX;
          position.y = y ;//* offsetY;
       }
       else {
          position.x = ( x + 0.5f );// * offsetX;
          position.y = y;// * offsetY;
       }     
       return position;
 }
 function CreateGrid()
 {
     go = GameObject.Find("Grid");
     var unitLengthv : float = ( useAsInnerCircleRadius )? (radius / (Mathf.Sqrt(3)/2)) : radius;
     
     offsetX =  Mathf.Sqrt(3);
     offsetY =  1.5f;
  
     for(var i : int = 0; i < formation.length; i++ )
     {
          for(var  j : int = 0; j < formation[i].length; j++ ) 
          {
             var  hexpos : Vector2 = HexOffset( i, j );
             var pos : Vector3 = new Vector3( hexpos.x, hexpos.y, 0 ) + transform.position;
             var tempsphere : Transform = Instantiate(sphere[formation[i][j]], pos, Quaternion.identity );
             tempsphere.transform.parent = go.gameObject.transform;
             if(formation[i][j] != E)
             {
                     tempsphere.transform.rigidbody.constraints = RigidbodyConstraints.FreezeAll;
             }
             tempsphere.GetComponent(CellScript).position = pos;
             tempsphere.GetComponent(CellScript).i = i;
             tempsphere.GetComponent(CellScript).j = j;
          }
     }
 }

code which i have tried :

 function OnCollisionEnter(collision : Collision )
 {        
     if(transform.parent == null)
     {      
         var gs : Grid = GameObject.Find("Grid").GetComponent(Grid);
         var hitColliders = Physics.OverlapSphere(collision.transform.position, 0.7);
         if(bubbleId.Equals(collision.gameObject.tag))
         {
              for (var i : int = 0; i < hitColliders.Length; i++) 
              {
                          
                    Destroy(hitColliders[i].gameObject);
                    gs.DestroySphere(hitColliders[i].gameObject.transform.GetComponent(CellScript).i ,hitColliders[i].gameObject.transform.GetComponent(CellScript).j , hitColliders[i].gameObject.transform.GetComponent(CellScript).position); 
                    Destroy(gameObject);           
              }
           }
          else
             {                            
                var contact : ContactPoint = collision.contacts[0];
             var pos : Vector3 = contact.point;    
             var t : Transform = ClosestTransform(pos);
             transform.position = t.position;
             transform.rotation = t.rotation;
             transform.rigidbody.velocity = Vector3.zero;
             transform.rigidbody.angularVelocity = Vector3.zero; 
             transform.rigidbody.isKinematic = true;
             
          }                                     
     }            
 }

cell script :

  public var  position : Vector3;
     public var color : String;
     public var i : int;
     public var j : int;

I am currently learning hex grid.. so pleaze guide me..

Thanks in advance for your support and help..