I need to find a Pub(suggestions?) that guides me on amending from one form to another.

First you need to go back and digest the response, including the part about Schedule A. I seriously doubt that you'll find it's to their advantage to itemize rather than take the standard deduction. They cannot take the employee business expenses plus the standard deduction.

If it actually does pay to itemize and amend you'll need Form 1040X and its separate instructions.

Phil
Rule Your Retirement Home Fool