You can assign a preferred vendor for items for purchase or resale. This can make things easier in that when you create a new purchase order, the preferred vendor of the first item will be selected. In addition, if you drop ship an item, NetSuite will automatically use the preferred vendor.
You can also link multiple vendors to an item. With administrator rights, click on the Setup tab, then Company>Enable Features. From the Items & Inventory tab, select the Multiple Vendors checkbox, then click Save.
Now, when you edit an item via Lists > Accounting > Items, you will see a drop-down list of vendors on the basic tab. You may add multiple vendors to the list. However, you may also select the preferred box next to one of these vendors to make it your preferred vendor for that item. Click Save to save your selection for this item.