Attaching/deleting documents to inventory items ~

In EBS 12.2.10, is there an API that can be called to attach a document to an inventory item (fnd_attached_documents.entity_name = 'MTL_SYSTEM_ITEMS') that will NOT kick off a concurrent request in the background?

I've gotten the document attached using two different programs, but both kick off a concurrent request per item.

So far I've tried these two:

fnd_attached_documents_pkg.insert_row

pon_attachments.add_attachment_frm_ui

They kick off a concurrent request per transaction.

Is there a better way to do a bulk update of inventory item attachments? our QA codes are being updated and we have about 1.4M deletions to do and 860k attachments.