Preparing for US FTA Post-Verification — Required Documents for Exporters and Suppliers

I am inquiring because I am handling FTA duties for the first time. Our company is a Tier 1 automotive vendor with a headquarters overseas; our Korean branch purchases CKD/SKD from domestic Tier 2 vendors and exports them (Importer = Overseas HQ, Exporter = Korean Branch, Supplier = Tier 2 Vendor). During export, the supplier directly registers the Blanket Certificate of Origin via their internal system, and based on that registration, our company issues and submits the Certificate of Origin. We do not separately verify whether the regional value content criteria are met. 1) In the event of a post-verification, what specific documents must the exporter and the supplier each prepare? 2) To prepare for post-verification, can we proactively request that suppliers submit a Declaration of Origin, Bill of Materials (BOM), and Manufacturing Process Chart?