Final answer:
In QuickBooks, both suppliers and vendors should be added to the Vendor List, as this is where you manage entities from whom you purchase goods or services, which is crucial for accounting and bookkeeping.
Step-by-step explanation:
If Sally the supplier and Van the vendor want to buy something from you in QuickBooks, you should add them to the Vendor List. In QuickBooks, both suppliers and vendors are managed under the Vendors section since they are considered entities from which you purchase goods or services. When you record transactions related to purchases or track accounts payable, you will do so under the vendor profiles you create for these contacts. This is part of the accounting and bookkeeping features within QuickBooks, which helps you manage your business finances more effectively.