WP multisite lost password redirection

functions.php

add_action('lostpassword_post', 'validate_reset', 99, 3);

function validate_reset(){
    if(isset($_POST['user_login']) && !empty($_POST['user_login'])){
        $email_address = $_POST['user_login'];

        //is this an email reset?
        if(filter_var( $email_address, FILTER_VALIDATE_EMAIL )){
            if(!email_exists( $email_address )){
                wp_redirect( $_POST['redirect_to'].'/register' );
                exit;
            } else {
                wp_redirect( $_POST['redirect_to'].'/register' );
            }
        }else{
        // if a username reset
            $username = $_POST['user_login'];
            if ( !username_exists( $username ) ){
                wp_redirect( $_POST['redirect_to'].'/register' );
                exit;
            } else {
                wp_redirect( $_POST['redirect_to'] );
                exit;
                }
            }

    }else{
      //user submitted nothing...
        wp_redirect( $_POST['redirect_to'].'/register' );
        exit;
    }
}


add_filter( 'lostpassword_url', 'my_lost_password_page', 10, 2 );
function my_lost_password_page( $lostpassword_url, $redirect ) {
    // /wp-login.php?action=lostpassword
    return home_url( '/wp-login.php?action=lostpassword&redirect_to=' . home_url() );
}