Setting Uploaded file of OneupUploaderBundle to form entity

Question

I'm using OneupUploaderBundle to upload files.
It uploads file and I can create a doctrine entity from uploaded files.
But after upload how can I set this files to main entity of my form?
for example I have a Post entity and OneupUploaderBundle created some File entities.
Now I want to:

1. Associate File entities to Post entity's OneToMany field
2. Delete those File entities if user never submit the Post form (delete orphan File entities)

How can I achieve this?