A supplier's part numbers rarely equal yours, so their deliveries show a wall of "not delivered" and "unexpected" lines. On a reconciliation, Same item on an unexpected line tells Cargora which of your lines it is; from then on that supplier's code matches your SKU on every delivery, PO completeness and invoice. Nothing is guessed: an alias exists only because a person confirmed it with both documents in front of them.
Open a reconciliation with unexpected lines and use Same item.