I have a big problem with Zoho Inventory. 

For example: Customer A makes an order. They want products X, Y and Z. I create the Sales Order and create the invoice, and send the invoice to the customer. The customer then calls to adjust the Sales Order. They don't want X any more, but they want Y and two of Z. 

I have already sent them the invoice for the original order, and their accounting team has it. So I cannot change this invoice or delete it. I want to give them a credit note for the original invoice, and send them a fresh new invoice for the products they have ordered. How can I do this?

I cannot edit or adjust the Sales Order without voiding or deleting any corresponding invoices.

If I void the invoice, I cannot invoice the products on this voided invoice again. 

There is no way in hell I can delete the original invoice, as it is a legal document and their accounts team already has it. 

So how do I adjust the sales order and give them a new invoice?