Hi Gang, I currently have 2 products (let's call them Product "A" and Product "B") on signup.php which are in the form of radio buttons like this: <input class="required" type="radio" id="product1" name="product_id[]" value="1" /> Select Product A <input class="required" type="radio" id="product2" name="product_id[]" value="2" /> Select Product B The customer must select one or the other to continue to the cc.php page to enter their payment information. Then, on the cc.php I want to offer an upsell for Product "C" in the form of a checkbox above the submit button like this: <input type="checkbox" id="product3" name="product_id[]" value="3" checked> Click to Upgrade to Product "C" I'm just not sure if I simply include a checkbox with the product ID if cc.php will pick up the extra product & append it to the customer's record as if I had assigned it as a hidden field in signup.php Please advise!