How to use withTrashed() in hasManyThrough relation

This is my Customer model

class Customer extends Model
{
    use SoftDeletes;
    protected $fillable  = ['name','place','address','provider','userid','senderid','pin','route','voicekey','burl','amc','amc_date','voice','active'];
    protected $dates = ['deleted_at','created_at','updated_at','amc_date'];

    public function User()
    {
        return $this->hasMany('SmSPortal\User');
    }    

    public function Student()
    {
        return $this->hasManyThrough('SmSPortal\Student','SmSPortal\User');
    }
}

Here i want to return results with students of trashed users.

iam tried follwing

Customer::find(2)->User()->Student()->get();

i tried this in model

    public function Student()
    {
        return $this->hasManyThrough('SmSPortal\Student','SmSPortal\User')->withTrashed();
    }

but its not working pls help me