duck

private var root : Clickable;

function Start() {

    if (root == this)
    {
        SpreadToChildren();
    }
}

function SetRoot(Clickable root)
{
    this.root = root;
}

function SpreadToChildren()
{
    for (Collider c in GetComponentsInChildren(Collider))
    {
        if (c.GetComponent(Clickable) == null)
        {
            c.gameObject.AddComponent(Clickable);
            c.SetRoot(this);
        }
    }
}