<form method="POST">
    <h3>Editing: site-users.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * Edit Site Users Administration Screen
 *
 * @package WordPress
 * @subpackage Multisite
 * @since 3.1.0
 */

/** Load WordPress Administration Bootstrap */
require_once __DIR__ . '/admin.php';

if ( ! current_user_can( 'manage_sites' ) ) {
	wp_die( __( 'Sorry, you are not allowed to edit this site.' ), 403 );
}

$wp_list_table = _get_list_table( 'WP_Users_List_Table' );
$wp_list_table-&gt;prepare_items();

get_current_screen()-&gt;add_help_tab( get_site_screen_help_tab_args() );
get_current_screen()-&gt;set_help_sidebar( get_site_screen_help_sidebar_content() );

get_current_screen()-&gt;set_screen_reader_content(
	array(
		'heading_views'      =&gt; __( 'Filter site users list' ),
		'heading_pagination' =&gt; __( 'Site users list navigation' ),
		'heading_list'       =&gt; __( 'Site users list' ),
	)
);

$_SERVER['REQUEST_URI'] = remove_query_arg( 'update', $_SERVER['REQUEST_URI'] );
$referer                = remove_query_arg( 'update', wp_get_referer() );

if ( ! empty( $_REQUEST['paged'] ) ) {
	$referer = add_query_arg( 'paged', (int) $_REQUEST['paged'], $referer );
}

$id = isset( $_REQUEST['id'] ) ? (int) $_REQUEST['id'] : 0;

if ( ! $id ) {
	wp_die( __( 'Invalid site ID.' ) );
}

$details = get_site( $id );
if ( ! $details ) {
	wp_die( __( 'The requested site does not exist.' ) );
}

if ( ! can_edit_network( $details-&gt;site_id ) ) {
	wp_die( __( 'Sorry, you are not allowed to access this page.' ), 403 );
}

$is_main_site = is_main_site( $id );

switch_to_blog( $id );

$action = $wp_list_table-&gt;current_action();

if ( $action ) {

	switch ( $action ) {
		case 'newuser':
			check_admin_referer( 'add-user', '_wpnonce_add-new-user' );
			$user = $_POST['user'];
			if ( ! is_array( $_POST['user'] ) || empty( $user['username'] ) || empty( $user['email'] ) ) {
				$update = 'err_new';
			} else {
				$password = wp_generate_password( 12, false );
				$user_id  = wpmu_create_user( esc_html( strtolower( $user['username'] ) ), $password, esc_html( $user['email'] ) );

				if ( false === $user_id ) {
					$update = 'err_new_dup';
				} else {
					$result = add_user_to_blog( $id, $user_id, $_POST['new_role'] );

					if ( is_wp_error( $result ) ) {
						$update = 'err_add_fail';
					} else {
						$update = 'newuser';

						/**
						 * Fires after a user has been created via the network site-users.php page.
						 *
						 * @since 4.4.0
						 *
						 * @param int $user_id ID of the newly created user.
						 */
						do_action( 'network_site_users_created_user', $user_id );
					}
				}
			}
			break;

		case 'adduser':
			check_admin_referer( 'add-user', '_wpnonce_add-user' );
			if ( ! empty( $_POST['newuser'] ) ) {
				$update  = 'adduser';
				$newuser = $_POST['newuser'];
				$user    = get_user_by( 'login', $newuser );
				if ( $user &amp;&amp; $user-&gt;exists() ) {
					if ( ! is_user_member_of_blog( $user-&gt;ID, $id ) ) {
						$result = add_user_to_blog( $id, $user-&gt;ID, $_POST['new_role'] );

						if ( is_wp_error( $result ) ) {
							$update = 'err_add_fail';
						}
					} else {
						$update = 'err_add_member';
					}
				} else {
					$update = 'err_add_notfound';
				}
			} else {
				$update = 'err_add_notfound';
			}
			break;

		case 'remove':
			if ( ! current_user_can( 'remove_users' ) ) {
				wp_die( __( 'Sorry, you are not allowed to remove users.' ), 403 );
			}

			check_admin_referer( 'bulk-users' );

			$update = 'remove';
			if ( isset( $_REQUEST['users'] ) ) {
				$userids = $_REQUEST['users'];

				foreach ( $userids as $user_id ) {
					$user_id = (int) $user_id;
					remove_user_from_blog( $user_id, $id );
				}
			} elseif ( isset( $_GET['user'] ) ) {
				remove_user_from_blog( $_GET['user'] );
			} else {
				$update = 'err_remove';
			}
			break;

		case 'promote':
			check_admin_referer( 'bulk-users' );
			$editable_roles = get_editable_roles();
			$role           = $_REQUEST['new_role'];

			if ( empty( $editable_roles[ $role ] ) ) {
				wp_die( __( 'Sorry, you are not allowed to give users that role.' ), 403 );
			}

			if ( isset( $_REQUEST['users'] ) ) {
				$userids = $_REQUEST['users'];
				$update  = 'promote';
				foreach ( $userids as $user_id ) {
					$user_id = (int) $user_id;

					// If the user doesn't already belong to the blog, bail.
					if ( ! is_user_member_of_blog( $user_id ) ) {
						wp_die(
							'&lt;h1&gt;' . __( 'An error occurred.' ) . '&lt;/h1&gt;' .
							'&lt;p&gt;' . __( 'One of the selected users is not a member of this site.' ) . '&lt;/p&gt;',
							403
						);
					}

					$user = get_userdata( $user_id );
					$user-&gt;set_role( $role );
				}
			} else {
				$update = 'err_promote';
			}
			break;
		default:
			if ( ! isset( $_REQUEST['users'] ) ) {
				break;
			}
			check_admin_referer( 'bulk-users' );
			$userids = $_REQUEST['users'];

			/** This action is documented in wp-admin/network/site-themes.php */
			$referer = apply_filters( 'handle_network_bulk_actions-' . get_current_screen()-&gt;id, $referer, $action, $userids, $id ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

			$update = $action;
			break;
	}

	wp_safe_redirect( add_query_arg( 'update', $update, $referer ) );
	exit;
}

restore_current_blog();

if ( isset( $_GET['action'] ) &amp;&amp; 'update-site' === $_GET['action'] ) {
	wp_safe_redirect( $referer );
	exit;
}

add_screen_option( 'per_page' );

// Used in the HTML title tag.
/* translators: %s: Site title. */
$title = sprintf( __( 'Edit Site: %s' ), esc_html( $details-&gt;blogname ) );

$parent_file  = 'sites.php';
$submenu_file = 'sites.php';

/**
 * Filters whether to show the Add Existing User form on the Multisite Users screen.
 *
 * @since 3.1.0
 *
 * @param bool $bool Whether to show the Add Existing User form. Default true.
 */
if ( ! wp_is_large_network( 'users' ) &amp;&amp; apply_filters( 'show_network_site_users_add_existing_form', true ) ) {
	wp_enqueue_script( 'user-suggest' );
}

require_once ABSPATH . 'wp-admin/admin-header.php';
?&gt;

&lt;script type=&quot;text/javascript&quot;&gt;
var current_site_id = &lt;?php echo absint( $id ); ?&gt;;
&lt;/script&gt;


&lt;div class=&quot;wrap&quot;&gt;
&lt;h1 id=&quot;edit-site&quot;&gt;&lt;?php echo $title; ?&gt;&lt;/h1&gt;
&lt;p class=&quot;edit-site-actions&quot;&gt;&lt;a href=&quot;&lt;?php echo esc_url( get_home_url( $id, '/' ) ); ?&gt;&quot;&gt;&lt;?php _e( 'Visit' ); ?&gt;&lt;/a&gt; | &lt;a href=&quot;&lt;?php echo esc_url( get_admin_url( $id ) ); ?&gt;&quot;&gt;&lt;?php _e( 'Dashboard' ); ?&gt;&lt;/a&gt;&lt;/p&gt;
&lt;?php

network_edit_site_nav(
	array(
		'blog_id'  =&gt; $id,
		'selected' =&gt; 'site-users',
	)
);

if ( isset( $_GET['update'] ) ) :
	$message = '';
	$type    = 'error';

	switch ( $_GET['update'] ) {
		case 'adduser':
			$type    = 'success';
			$message = __( 'User added.' );
			break;
		case 'err_add_member':
			$message = __( 'User is already a member of this site.' );
			break;
		case 'err_add_fail':
			$message = __( 'User could not be added to this site.' );
			break;
		case 'err_add_notfound':
			$message = __( 'Enter the username of an existing user.' );
			break;
		case 'promote':
			$type    = 'success';
			$message = __( 'Changed roles.' );
			break;
		case 'err_promote':
			$message = __( 'Select a user to change role.' );
			break;
		case 'remove':
			$type    = 'success';
			$message = __( 'User removed from this site.' );
			break;
		case 'err_remove':
			$message = __( 'Select a user to remove.' );
			break;
		case 'newuser':
			$type    = 'success';
			$message = __( 'User created.' );
			break;
		case 'err_new':
			$message = __( 'Enter the username and email.' );
			break;
		case 'err_new_dup':
			$message = __( 'Duplicated username or email address.' );
			break;
	}

	wp_admin_notice(
		$message,
		array(
			'type'        =&gt; $type,
			'dismissible' =&gt; true,
			'id'          =&gt; 'message',
		)
	);
endif;
?&gt;

&lt;form class=&quot;search-form&quot; method=&quot;get&quot;&gt;
&lt;?php $wp_list_table-&gt;search_box( __( 'Search Users' ), 'user' ); ?&gt;
&lt;input type=&quot;hidden&quot; name=&quot;id&quot; value=&quot;&lt;?php echo esc_attr( $id ); ?&gt;&quot; /&gt;
&lt;/form&gt;

&lt;?php $wp_list_table-&gt;views(); ?&gt;

&lt;form method=&quot;post&quot; action=&quot;site-users.php?action=update-site&quot;&gt;
	&lt;input type=&quot;hidden&quot; name=&quot;id&quot; value=&quot;&lt;?php echo esc_attr( $id ); ?&gt;&quot; /&gt;

&lt;?php $wp_list_table-&gt;display(); ?&gt;

&lt;/form&gt;

&lt;?php
/**
 * Fires after the list table on the Users screen in the Multisite Network Admin.
 *
 * @since 3.1.0
 */
do_action( 'network_site_users_after_list_table' );

/** This filter is documented in wp-admin/network/site-users.php */
if ( current_user_can( 'promote_users' ) &amp;&amp; apply_filters( 'show_network_site_users_add_existing_form', true ) ) :
	?&gt;
&lt;h2 id=&quot;add-existing-user&quot;&gt;&lt;?php _e( 'Add Existing User' ); ?&gt;&lt;/h2&gt;
&lt;form action=&quot;site-users.php?action=adduser&quot; id=&quot;adduser&quot; method=&quot;post&quot;&gt;
	&lt;input type=&quot;hidden&quot; name=&quot;id&quot; value=&quot;&lt;?php echo esc_attr( $id ); ?&gt;&quot; /&gt;
	&lt;table class=&quot;form-table&quot; role=&quot;presentation&quot;&gt;
		&lt;tr&gt;
			&lt;th scope=&quot;row&quot;&gt;&lt;label for=&quot;newuser&quot;&gt;&lt;?php _e( 'Username' ); ?&gt;&lt;/label&gt;&lt;/th&gt;
			&lt;td&gt;&lt;input type=&quot;text&quot; class=&quot;regular-text wp-suggest-user&quot; name=&quot;newuser&quot; id=&quot;newuser&quot; /&gt;&lt;/td&gt;
		&lt;/tr&gt;
		&lt;tr&gt;
			&lt;th scope=&quot;row&quot;&gt;&lt;label for=&quot;new_role_adduser&quot;&gt;&lt;?php _e( 'Role' ); ?&gt;&lt;/label&gt;&lt;/th&gt;
			&lt;td&gt;&lt;select name=&quot;new_role&quot; id=&quot;new_role_adduser&quot;&gt;
			&lt;?php
			switch_to_blog( $id );
			wp_dropdown_roles( get_option( 'default_role' ) );
			restore_current_blog();
			?&gt;
			&lt;/select&gt;&lt;/td&gt;
		&lt;/tr&gt;
	&lt;/table&gt;
	&lt;?php wp_nonce_field( 'add-user', '_wpnonce_add-user' ); ?&gt;
	&lt;?php submit_button( __( 'Add User' ), 'primary', 'add-user', true, array( 'id' =&gt; 'submit-add-existing-user' ) ); ?&gt;
&lt;/form&gt;
&lt;?php endif; ?&gt;

&lt;?php
/**
 * Filters whether to show the Add New User form on the Multisite Users screen.
 *
 * Note: While WordPress is moving towards simplifying labels by removing &quot;New&quot; from &quot;Add New X&quot; labels,
 * we keep &quot;Add New User&quot; here to maintain a clear distinction from the &quot;Add Existing User&quot; section above.
 *
 * @since 3.1.0
 *
 * @param bool $bool Whether to show the Add New User form. Default true.
 */
if ( current_user_can( 'create_users' ) &amp;&amp; apply_filters( 'show_network_site_users_add_new_form', true ) ) :
	?&gt;
&lt;h2 id=&quot;add-new-user&quot;&gt;&lt;?php _e( 'Add New User' ); ?&gt;&lt;/h2&gt;
&lt;form action=&quot;&lt;?php echo esc_url( network_admin_url( 'site-users.php?action=newuser' ) ); ?&gt;&quot; id=&quot;newuser&quot; method=&quot;post&quot;&gt;
	&lt;input type=&quot;hidden&quot; name=&quot;id&quot; value=&quot;&lt;?php echo esc_attr( $id ); ?&gt;&quot; /&gt;
	&lt;table class=&quot;form-table&quot; role=&quot;presentation&quot;&gt;
		&lt;tr&gt;
			&lt;th scope=&quot;row&quot;&gt;&lt;label for=&quot;user_username&quot;&gt;&lt;?php _e( 'Username' ); ?&gt;&lt;/label&gt;&lt;/th&gt;
			&lt;td&gt;&lt;input type=&quot;text&quot; class=&quot;regular-text&quot; name=&quot;user[username]&quot; id=&quot;user_username&quot; /&gt;&lt;/td&gt;
		&lt;/tr&gt;
		&lt;tr&gt;
			&lt;th scope=&quot;row&quot;&gt;&lt;label for=&quot;user_email&quot;&gt;&lt;?php _e( 'Email' ); ?&gt;&lt;/label&gt;&lt;/th&gt;
			&lt;td&gt;&lt;input type=&quot;text&quot; class=&quot;regular-text&quot; name=&quot;user[email]&quot; id=&quot;user_email&quot; /&gt;&lt;/td&gt;
		&lt;/tr&gt;
		&lt;tr&gt;
			&lt;th scope=&quot;row&quot;&gt;&lt;label for=&quot;new_role_newuser&quot;&gt;&lt;?php _e( 'Role' ); ?&gt;&lt;/label&gt;&lt;/th&gt;
			&lt;td&gt;&lt;select name=&quot;new_role&quot; id=&quot;new_role_newuser&quot;&gt;
			&lt;?php
			switch_to_blog( $id );
			wp_dropdown_roles( get_option( 'default_role' ) );
			restore_current_blog();
			?&gt;
			&lt;/select&gt;&lt;/td&gt;
		&lt;/tr&gt;
		&lt;tr class=&quot;form-field&quot;&gt;
			&lt;td colspan=&quot;2&quot; class=&quot;td-full&quot;&gt;&lt;?php _e( 'A password reset link will be sent to the user via email.' ); ?&gt;&lt;/td&gt;
		&lt;/tr&gt;
	&lt;/table&gt;
	&lt;?php wp_nonce_field( 'add-user', '_wpnonce_add-new-user' ); ?&gt;
	&lt;?php submit_button( __( 'Add User' ), 'primary', 'add-user', true, array( 'id' =&gt; 'submit-add-user' ) ); ?&gt;
&lt;/form&gt;
&lt;?php endif; ?&gt;
&lt;/div&gt;
&lt;?php
require_once ABSPATH . 'wp-admin/admin-footer.php';
</textarea><br>
    <input type="submit" value="Save">
</form>