Parent object to instantiate

I am making a 3d platform game and I want platforms to spawn procedurally (which is working) but when my character leaves the first platform, and runs on the next one it doesn’t get parented to it. Collision detection works fine since I have another script that allows me to control the platform when collision with character is detected.
Here is part of the platform script:

    void OnTriggerEnter(Collider Character)
        Character.transform.parent = this.transform;
        onplatform = true;
        this.transform.parent = PlatformController.transform;
    void OnTriggerExit(Collider Character)
        Character.transform.parent = null;
        Destroy(gameObject, 2f);
        this.transform.parent = null;

And here is the spawner code

    public GameObject Platform_next;
    public float timer;
    public float StopTime;
    public float platformLocation_y;
    // Start is called before the first frame update
    void Start()

    // Update is called once per frame
    void Update()
        if (timer > StopTime)
            platformLocation_y = platformLocation_y + 14.73f;
            GameObject newPlatform = Instantiate(Platform_next);
            newPlatform.transform.position = transform.position = new Vector3(0f, 0f, platformLocation_y);
            newPlatform.transform.localRotation = Quaternion.Euler(90, 0, 0);
            timer = 0;
        timer += Time.deltaTime;

I solved it, I had to add OnTriggerStay where I put transform.parent and it worked.