Form1 and Form2

//Form1.php

<?php
session_start();
//check input fields for error
$errors = '';
if(
   empty($_POST['address']))
{
    $errors .= "\n Error: all fields are required";
}
// store input values
$_SESSION['address'] = $_POST['address'];
//redirect to second page
if( empty($errors))
{
    header('Location: second_page.php');
}
?>

//Form2.php

<?php
session_start();

//check input fields for error
$errors = '';
if(
   empty($_POST['comment']))
{
    $errors .= "\n Error: all fields are required";
}

$_SESSION['condition_home'] = $_POST['condition_home'];
$_SESSION['selling_plan'] = $_POST['selling_plan'];
$_SESSION['comment'] = $_POST['comment'];
//redirect to second page
if( empty($errors))
{
    header('Location: third_page.php');
}
?>