You are trying to insert a new field into the orders table ...

But, you are trying to do this at the wrong point ...

Gather the information to a $_SESSION variable such as $_SESSION['ship_complete'] where the value is 0 or 1 ...

Then in the order.php if you were to follow everywhere the ip_address is managed ... that is where you need to add your ship_complete ...

Now so that the data is managed in all the other files of the checkout right ... look how the comment is handled ... and you would use your ship_complete in the same manner so that it carries from page to page ...

So "collecting" the information for the new field ship_complete follows the comment ... and "adding" the new field ship_complete follows the ip_address ...

Easy smeazy ... eh?!