Inventory Corrections

Hey People,

We have an item with Costing Method : FIFO, there are 2 items involved in this problem. Item A & ItemB

Purchased Item : A - Qty 100 @ 3.14 = 314
realised that it should be item B instead, so the user did a negative adjustment to Item A and postive Adjustment to B I know it should have been a credit memo and invoice however this is already done so cannot change this.

now the problem is that the cost is gone wrong on item B, any ideas how to fix this problem ?

Thanks,