Hi, I'm Ashik. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP
There is a way to make multiple scans to single PDF using Epson Scan. Open the Epson Scan app. In Epson Scan app, you will see Mode option at top right or on the main screen. Click it and select Home mode or Professional Mode.
Then click on File Save settings button which is usually on the bottom right. Under Image Format, select PDF. Click OK and do a scan. After scanning first document, you will get a message asking you to Add, Edit Page or Save. Click Add and you can do further scans. Save one you scanned all of your documents and you will get them in Single PDF file.
If you have any difficulty on following the steps above, please let me know and I will continue to help you