Multiple attachment to PO workflow

I am trying to attach multiple documents attached to the PO to PO workflow notification. The documents always get overwritten and only the last document gets attached to the notification. Can this be achieved? I am using 'PLSQLBLOB:XX_AME_APPR_PKG.set_po_attachment/'||l_document_id);

PROCEDURE set_po_attachment (
    document_id IN VARCHAR2
  , display_type IN VARCHAR2
  , document IN OUT BLOB
  , document_type IN OUT VARCHAR2)
IS
    c_module CONSTANT VARCHAR2(100) := 'XX_AME_APPR_PKG.set_po_attachment';
   
    l_invoice_id   VARCHAR2(100) := document_id;
    l_lob_id       NUMBER;
    l_bdoc         BLOB;
    l_content_type VARCHAR2(100);
    l_filename     VARCHAR2(300);