Adding a text box to check out.

-- url of the page with the problem -- : www.southernempress.com
-- HikaShop version -- : 2.3.1 Business
-- Joomla version -- : 3.2
-- PHP version -- : 5.4
-- Browser(s) name and version -- : XXXXX x.x

I would like to add a text box to gather further information after my guest has entered a coupon. Here is the US we have Groupon, and I have that all set up, but there is an additional code that I could use that information for.

Can I add a conditional text box after a good coupon code is entered in the Display>Views area, or just some way to add a box during check out.

Thanks for your help.

Cheers for now,
Everett