How to pass entry for RMA (return material authorization)

Ok.

So here’s till where i could understand:

Sale Invoice:

Say, out of 5 Books, 1 book came back to us for replacement.

So, I created a Credit Note for the Customer:

Now my Inventory (Book) Shows as follows:

Then i issue Debit Note to Supplier:

So now the Inventory is as below:

So I understood the Step 1 and Step 2

But could you please explain in brief, Step 3 and Step 4.

Want I wanted to do in step 3 is, give the stock in hand (Book 1 quantity) to the Client.
For this, i need to create a New Sales Invoice?

If yes, then the Inventory will show zero balance. And

Step 4 would be creating new Purchase Invoice of the replaced inventory (Book)

But the value of Sales Invoice and Purchase Invoice will be 0.00/- right?
Only the quantity is what needs to reflect as per the physical stock.

If this is the case, i pretty much understood the process.

Thank you.