Add extra text input for file field
I would recommend using the field collection module instead. Create a field collection with a file upload field, description field and file owner field (can be a text field or user reference field. Set the field collection to unlimited. Then add the field collection to your page content type. It will allow you to do more custom things moving forward.

https://www.drupal.org/project/field_collection 
https://www.drupal.org/project/references