Simple Relation Help

I have 3 tables

Category SubCategory And Sub Child

Now i want to show sub childs having category and subcategory

Sub child table fields

id
category_id
sub_cat_id
title
slug 

My Sub Child Model Function

public function sub_category()
{
        return $this->hasManyThrough('App\Category','App\SubCategory', 'category_id', 'sub_cat_id');
}

How want to show sub child categories having category and sub category Help Needed

Here is my Model of sub child table