I have two zaps atm and they are working good.

First zap (Step 1: First contact) is like this:

Convertforms → Is this first contact?  Lookup Spreadsheet Row in Google sheet.  (Create Google Sheets Spreadsheet Row if it doesn’t exist yet?)

When this is hapening there will be send a email by convertforms to us.  We will reply this with a new convertforms form.

Second zap is a bit the same (Step 2: Need more info)
Convertforms → Lookup Spreadsheet Row in Google sheet.  (Create Google Sheets Spreadsheet Row if it doesn’t exist yet?)

I think you already understand where my problem is. In the first contact form in convertforms, the user can enter his first name, last name, email address and some information. In the second form, additional information must be entered, but the user must re-enter the information that he had already entered in the first email. I think this is a shame because it doesn't come across as professional. How can I connect those two forms? For example, I want to give the user a direct link to a second form where he can edit the row (unique value is his email address). However, it must also be so secured that, for example, he cannot change the data of another person by simply changing the email address.