Can I add a required upload document button?

I am looking for a site that will help me organize a film shoot with 300 extras. I want to create an RSVP form that we send out via email, that has all the information, and that won't let them RSVP without uploading a document (their signed release form). 

Something that won't let them click "yes" without the upload of a pdf/doc - we don't want anyone to be able to get on the list without first giving us their consent to be on camera. 

Let me know if you think this is possible!

The File Upload field can be set as required so cannot be left unfilled when the form is being submitted.

Here are other guides that you may also find useful in creating your form with an Upload Field.

How-to-Create-File-Upload-Forms

Changing-the-File-Upload-Size-Limit

How-to-Change-the-Allowed-File-Types-in-the-Upload-Field

How-to-Download-the-Submission-Files

If you have other questions or concerns, please feel free to let us know.