¿Why wont child move with parent?

So, I have a grenade without any physics while the player doesnt pickup it. It's a trigger with no rigidbody. When the player picks it up, a rigidbody2D is added, Trigger is set to false, and collisions with the player are set to be ignored. Also, rigidbody is set to kinematic (true). So, whats bad? The object will stay at air, not moving. Thanks in advance

     void OnTriggerStay2D(Collider2D other)
     {
         if (Input.GetKeyDown(KeyCode.E) || (controls.E == true))
         {
             if ((other.tag == "player"))
             {
                 GetComponent<BoxCollider2D>().isTrigger = false;
                 gameObject.AddComponent<Rigidbody2D>();
                 GetComponent<Rigidbody2D>().isKinematic = true;
                 Physics2D.IgnoreCollision(GetComponent<BoxCollider2D>(), other, true);
                 transform.position = other.transform.position;
                 transform.rotation = other.transform.rotation;
                 transform.parent = other.transform;
             }
         }
     }