Toggle between to active gameobjects while child's only activate when the parent is clicked using c#??

I tend to avoid static variables in general. But I they seem to be a good way to communicate between different objects in the same class, often producing cleaner solutions than the alternatives. So for your code, you can do something like this:

 public static Component Play1;
 public static Component Play2;
 public GameObject[] Player = new GameObject [7];

 private static GameObject goSelected = null;
 private bool selected = false;

 void Update() {
     if (selected && goSelected != gameObject) {
         for (int i = 0; i < Player.Length; i++) {
             if (Player [i]) {
                 Player [i].SetActive (false);
             }
         }
         selected = false;
     }
 }
 
 void OnMouseEnter ()
 {
     //change text color
     renderer.material.color = Color.black;
 }
 
 void OnMouseExit ()
 {
     //change text color
     renderer.material.color = Color.white;
 }
 
 void OnMouseDown()
 {
     for (int i = 0; i < Player.Length; i++) {
         if (Player [i]) {
             Player [i].SetActive (true);
         }
     }
     goSelected = gameObject;
     selected = true;
 }