How to book

I got the steps in handling the payment received from another customer and ensured the person who paid it would receive a copy of the transaction, BT5509.

In QuickBooks Online, when you receive or record the payment, you need to select the customer linked to the invoice for the transaction to show up. If you choose another person, it will not appear, and you cannot link it.
 

In such cases that another customer is paying the invoice, it's best to receive the payment by selecting the linked client and adding a note in the Memo field indicating that the payment is being made by someone else. This process will ensure the transaction will be closed and marked as paid.

1. Hover over the Sales menu. Look for the invoice.
2. Click Receive payment. Tick the associated transaction.
3. Scroll down and type in who paid it in the Memo field. 
4. Hit Print, then manually send a copy of the receipt to the customer who paid it. 

Additionally, I recommend seeking advice from your accountant for alternative approaches to handling payments made by another customer. Doing so will help maintain accurate financial records. If you don't have one, you can find a professional through this link: https://quickbooks.intuit.com/find-an-accountant/.

Moreover, you can transfer credit from one customer to another in QuickBooks Online. This feature allows you to easily manage and move credits between clients as needed within the platform.

Let me know if you need further help with this or anything else. I'll get back to you. Have a good one, BT5509!