How to reset a child object to its parent

I am making a block buster type of game, and I am trying to get the ball to reset to the paddle after it goes off screen. I have the ball set as a child of the paddle initially so that they move together when the game starts, but I have a launch script for the ball that removes the ball as a child of the paddle so it can bounce around independently. The problem I am having is when the ball goes off screen (when a life would be lost), I can’t get the ball to reset back to the paddle. One thought I had was to destroy the ball and paddle when the ball collides with the dead zone at the bottom of the screen (i placed a cube below the view of the camera to detect collision), and then Instantiate the entire Ball/Paddle game object. I am fairly new to using Unity and C# though, and have no clue how to achieve the desired result.

try this code:

ball.transform.parent = paddle.transform;

put it in any function.