How to add supplier invoices with credit (not prepaid bills or expenses) to QB app?

Hello, -upgradevip-com.

 I want to ensure this is taken care of, but I have questions about your concern first.

Can you please let me know what you're trying to achieve? Are you trying to record a vendor refund? Any additional details will help me provide accurate data and resolutions as soon as possible.

In the meantime, check to record a customer refund or supplier refund in QuickBooks Online. This will show you how to record a refund based on various scenarios. 

Keep me updated in the comments below. Take care!