FileField Permissions- How can I allow users to upload a file without giving them the ability to remove files that have been uploaded? I want to be able to upload a file into an article but without the ability to remove other files uploaded from other users to the same article.

Is it possible?

I tried the Field Permissions module; I can edit, but I cannot upload.
Try to add a second file field via the field UI; to set the permissions for a single field you could use hook_field_access().