There are instances when you process a payment and have it applied to two separate vendors. In this instance, there's a setting called Sub Vendors.
This is most commonly used when a hotel is processing a payment to a credit card company, but that credit card was used to purchase items from another vendor. For example, you use your American Express to make a purchase at Home Depot. The invoice should be entered to American Express, but when you enter the COA, you can select an option for SubVendor to add Home Depot. The purpose of this is so that you can track expenses paid to HD Supply, or the other vendors you purchased items from.
To add a Sub Vendor, after you complete the top part of the invoice entry, scroll down to the COA detail section. On the top right Column Icon, select the icon, then select Sub Vendor.
If you always want the Sub Vendor to show for this vendor, you can select Save as Default View.
Clicking the checkbox next to Sub Vendor will add this column to the COA detail screen as shown.
Here is how it will appear:
This will then allow you to Search in Accounting to find details related to American Express, who the payment was processed to, or to Home Depot, where the expense occurred.