Jotform follow up survey -- spreadsheet to form?

Hi, I am creating one form at the moment.

Let's say the first form, an order form, allows a user to enter:

Name:
ProductA: (numeric quantity)
ProductB: (numeric quantity)
Product C: (numeric quantity)

So at a later stage, can I produce a second form, with Spreadsheet to form widget (providing a unique key for each user), to lookup their order, and based on the order details (like if they ordered ProductA), ask follow up questions specific to ProductA. (And also hide questions about ProductA if they did not order ProductA.)

(1) Is this how the Spreadsheet to form widget is used?

(2) Can I use two columns (two fields) as the unique key to look up the info? Like how many websites, someone can lookup their order status by using their email and order#. (not sensitive information that requires login, but requires one to have both the email and the order# to lookup the info.)

(3)Also I saw this here:

https://www.jotform.com/answers/739230-Is-there-a-way-to-build-a-form-with-a-client-login-system

"A workaround I can suggest is to add a "Unique key" field with a condition that only users who has the correct key can submit the form."

(a) how do you do this? Or is it the same spreadsheet to form widget. 

(b) is there a way after the user enters the key, I can access/refer to a second column without populating it in the form? So like in (2), after the key is entered, I want them to enter in their email and check if that matches the record the key pulled up. I wouldn't want to populate the field, even if it's hidden (cause then it will still sit in the html code). But I want to refer it.

thanks

(1) Is this how the Spreadsheet to form widget is used?

Please note that when you add spreadsheet to form widget in form, you will need to upload excel file with data in the widget. Once the excel data is uploaded, user will be able to input data in id field and accordingly the fields of the form with will be populated with data from excel file.

Once the data in respective fields is populated, you can add condition in form to show/hide the data based on the field value. 

It cannot be used to automatically get the data from the submissions of other forms and populate your form field. 

You may like to take a look at the following guide should help you on spreadsheet to form widget:  https://www.jotform.com/help/442-How-to-Use-the-Spreadsheet-to-Form-Widget 

(2) Can I use two columns (two fields) as the unique key to look up the info? 

Unfortunately no, it is not possible to combine two fields of form to make it a unique field / value.

(a) how do you do this? Or is it the same spreadsheet to form widget. 

No, it is achieved by adding condition in form field to show / hide form fields based on the input value of user in another field. You may like to take a look at the following  thread where I have explained step by step on how to achieve this:  https://www.jotform.com/answers/1589503-Is-it-possible-to-password-protect-my-form 

(b)

Unfortunately no, the only possibility is to pass the data form one form to another form by taking advantage of "URL Parameter" feature.

Hope this helps.

Do get back to us if you have any questions.