Thank you for your reply.
I'm a bit confused in following your direction, so can I confirm about what you've mentioned?
1. My order form goes like this;
Order Form (extended version of contact form, used CSS Form Builder, not eCart.)
—> Confirm page with submit button with Universal Email function.
Now, The only form elements in Confirm page are the two buttons of Modify and Submit. Do I add a set session value to these button?
Should I still use eCart's set session value?
Or should I use WA Cookies Toolkit?
(Since I haven't used eCart for this form at all.)
2. You say "on the checkout page", so in my case, this could be the order form page, as it is the page you go and type in your info and ordering contents?
Hope I'm making a sense.