The Highway Conveyance Document can be changed or amended depending on the status of the document. After you have submitted a Highway Conveyance Document, you can edit your document and add the additional CCNs. Please refer to section 6.6 (Editing a Submitted Document) of the eManifest Portal User Guide for more information. https://www.cbsa-asfc.gc.ca/prog/manif/portal-portail/guide-eng.html.