PID Control Object (with questions)

regarding attaching/uploading of multiple files: I did not figure out how to do it at once, but one after the other work:

1. enter/edit the post
   
2. upload a file
   
3. save
   
4. more files, go to 1.
   
   

Also with deleting and adding again I had trouble... therefore, after every file upload or delete, save the post and edit it again with a delete or update. (I recall vaguely that deleting more than one file in one edit/save session worked.)