How to combine submissions in one Google Spreadsheet file?

I am trying to use your option 2, i.e using Google Spreadsheet but I have noticed that every time I do an integration from another form, it creates a new spreadsheet with the same name and not just collect the submissions into just 1 file. Is there a way around this as that won't combine the submissions.

Unfortunately, the spreadsheet will not collect the submissions from 2 forms into one file, even if the name is the same. Every time you integrate a from with google spreadsheet, a new spreadsheet will be created. For more information on the integration, you can check out this guide: How to Integrate Form with Google Spreadsheet

You can try using this add-on to merge the two sheets together: Merge Sheets Add-on. However, do note that doing this might cause issues with the integration of google spreadsheet with the form. The next submissions may not be received in the spreadsheet correctly.

A possible alternative would be to use the Combine Submissions App to combine the submissions: http://apps.jotform.com/app/combine_submissions 

If you need further assistance, do let us know.