How can i define the order of blogs in a multisite network manually (like pages)?

I ended up implementing my idea.

I’ve described the creation of the custom input field on the Site Info Screen unter Network in this Post. Here is the complete code again:

<?php
// Create custom Input Field on the WP-Admin > Network > Site Info Screen
// for the possibility to order sites manually 
add_action('admin_footer', 'pg_custom_site_options');
function pg_custom_site_options(){

    global $pagenow;

    if( 'site-info.php' == $pagenow ) {

        global $details;

        $blog_id = isset( $_REQUEST['id'] ) ? intval( $_REQUEST['id'] ) : 0;
        if ( ! $blog_id ) wp_die( __('Invalid site ID.') );

        $saved_value = get_blog_option( $blog_id, 'blog_order');

        ?>
        <table style="display: none;">
            <tr id="user16975_custom_options">
                <th scope="row">Order</th>
                <td><input type="text" size="5" name="blog[blog_order]" value="<?php echo esc_attr( $saved_value ) ?>" ></td>
            </tr>
        </table>
        <script>
            jQuery(function($){
                $('.form-table tbody').append($('#user16975_custom_options'));
            });
        </script>
        <?php

    }
}

add_action('admin_init', 'pg_save_custom_site_options');
function pg_save_custom_site_options(){

    global $pagenow;

    if( 'site-info.php' == $pagenow &&
        isset($_REQUEST['action']) &&
        'update-site' == $_REQUEST['action']
    ) {
        // Use a default value here if the field was not submitted.
        $new_field_value="0";

        if ( isset( $_POST['blog']['blog_order'] ) ) {
            $new_field_value = intval( $_POST['blog']['blog_order'] );

            // save option into the database
            if( is_int($new_field_value) ){
                update_blog_option( $_POST['id'], 'blog_order', $new_field_value );
            }

        }

    }
}
?>

After every site got its order number i’ve placed it in the wp_get_sites-array

$all_standorte =  wp_get_sites( $args );

// Get the order nr of each site and save it in the array
$pos = 0;
foreach( $all_standorte as $standort){

    $standort_id = $standort['blog_id'];

    $blog_order = get_blog_option( $standort_id, 'blog_order', '0');

    $all_standorte[$pos]['blog_order'] = $blog_order;

    $pos++;
}

The final step is sorting the array with usort().

// Sort Sites by Custom Order
function sort_sites_by_order($a, $b){

    // ascending (aufsteigend)
    return $a['blog_order'] - $b['blog_order'];

    // descending (absteigend, der juengste Artikel zuerst)
    // return $b['blog_order'] - $a['blog_order'];
}
usort($all_standorte, 'sort_sites_by_order');