I want to check if i am thinking in right direction and if not would like some guidance on approach. My use case is as follows: A user will upload an excel/csv file using a force.com unauthenticated sites. However, we would like to ensure that right user is uploading by doing a pseudo user validation like entering a pin which upon validation allows user to file upload screen to upload the csv file. This will then need to parse the file and upsert after performing few file checks. can we use flows to capture the user pin and validation and there by invoke a visualforce page from flow for file upload and insert?
Thanks !