Make childs for custom post type in WordPress?

I need help!
I have create a custom post type in my theme and it worked. It has result:

• mysitename.co/collage/harvard

I want new childs that can be added, I mean like this:

• mysitename.co/collage/harvard/address

• mysitename.co/collage/harvard/students

from above where the “address and students” is child from harvard.

My current code is:

add_action('init', 'register_segala_Collage');

function register_all_list_Collage() {

    $labels = array( 
        'name' => _x('Collage', 'newborne'),
        'singular_name' => _x('Collage', 'newborne'),
        'all_items' => _x('All Collage', 'newborne'),
        'add_new' => _x('Add List Collage', 'newborne'),
        'add_new_item' => _x('Add List Collage', 'newborne'),
        'edit' => _x('Edit List Collage', 'newborne'),
        'edit_item' => _x('Edit List Collage', 'newborne'),
        'new_item' => _x('New Collage', 'newborne'),
        'view' => _x('View Collage', 'newborne'),
        'view_item' => _x('View Collage', 'newborne'),
        'search_items' => _x('Search Collage', 'newborne'),
        'not_found' => _x('No Collage Found', 'newborne'),
        'not_found_in_trash' => _x('No Collage Found', 'newborne'),
        'menu_name' => _x( 'Collage', 'newborne' ),
    );

    $args = array(
        'labels' => $labels,
        'public' => true,
        'capability_type' => 'post',
        'rewrite' => array( 'slug' => 'Collage' ),
        'query_var' => true,
        'exclude_from_search' => true,
        'menu_position' => 5,
        'menu_icon' => 'dashicons-nametag',
        'supports' => array('title', 'editor', 'thumbnail')
    );
    register_post_type( 'Collage', $args );
}

How can I do that? is there any code?
Thanks in help.