2D GUI Group moving with players.

I have four players that have health and energy. The bars should all float just above the player's heads, and move/update along with them.

I cannot figure out how to make the gui I have move, specifically because I'm using a "group", and I'm not sure I fully understand it, or what to use instead.

Here is the current code I use, which only places it in the corner:

 var barDisplay : float = 0;
 var pos : Vector2 = new Vector2(20,40);
 var size : Vector2 = new Vector2(60,20);
 var healthBarEmpty : Texture2D;
 var healthBarFull : Texture2D;
  
 function OnGUI()
 {
  
     // draw the background:
     GUI.BeginGroup (new Rect (pos.x, pos.y, size.x, size.y));
         GUI.Box (Rect (0,0, size.x, size.y),healthBarEmpty);
  
         // draw the filled-in part:
         GUI.BeginGroup (new Rect (0, 0, size.x * barDisplay, size.y));
             GUI.Box (Rect (0,0, size.x, size.y),healthBarFull);
         GUI.EndGroup ();
  
     GUI.EndGroup ();
  
 } 
  
 function Update()
 {
     // for this example, the bar display is linked to the current time,
     // however you would set this value based on your desired display
     // eg, the loading progress, the player's health, or whatever.
     barDisplay = health;
 }

Health is a separate variable that starts at 100 and decreases as they take damage.

I considered just using several drawn boxes, and changing the size of that. Would that be a suitable way to do this? Is there an easy way to move this group?