Adding one Objects Rotation To Another Objects Rotation

I want to add one objects Y Rotation to another Objects Y Rotation. I currently have it adding the roatation however it is adding it continuously, and i want it to do it for 1 frame.`using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class RotationAdd_V2 : MonoBehaviour {

public GameObject Leader;
public GameObject Follower;



// Use this for initialization
void Start () {

}



// Update is called once per frame
void Update () {

	Follower.transform.rotation = Quaternion.Euler(Follower.transform.rotation.eulerAngles.x, Follower.transform.rotation.eulerAngles.y + Leader.transform.rotation.eulerAngles.y, Follower.transform.rotation.eulerAngles.z);

}

}

You can apply multiple quaternion rotations by multiplying them together.

The order determines which rotation is applied first:

transform.rotation = FirstQuaternion * SecondQuaternion * ThirdQuaternion.