When an item is ordered from a Vendor, that Vendor is added to the item's Vendor Information Screen in the Line 1 position. Any Vendors already on the Vendor Information Screen are rotated down by one line each. If the Vendor Information Screen already has four other Vendors, the Vendor in the Line 4 position is dropped when the Vendors are rotated.
This method works well if most or all items are frequently ordered from many different Vendors.
The Rotate Vendors parameter in the Purchase Manager Update Parameters must be enabled to rotate the Vendor Information.