Hello, amexpert.

I'll take it from here and lay down the details about MadelynC's answer when handling sub-vendors. 

QuickBooks Desktop doesn't support sub-vendors. 

To clarify MadelynC's answer, you can use the Add/Edit Multiple List Entries function to add Vendor B to your vendors list in QuickBooks. 

When you create a bill or any expense transactions, use the Memo field to indicate that you bought items from Vendor B but billed through Vendor A. 

If you need to take a look at your vendor transactions or any other financial data, you can check this article for a guide: Understand reports.

Do you need to enter other lists or want to record specific transactions? Or do you have any other concerns with QuickBooks Desktop? Please let me know the details below and I'll guide you through the process.