Cost of Return to Receiving transaction

Using Oracle e-Business Suite 12.2.7

We use FIFO to account for Inventory. There are 2 receipts of the same item having the same quantity but the price is different. There are 2 layers created by these receipts. Quantity received under both receipts is fully available at the warehouse, it has not been issued yet. Then Receipt #2 is Returned or Corrected. Which layer is affected by these transactions and what should be the cost of Return or Correction (layer #1 cost or Layer #2 cost)?

Thank you!