How to achieve costing for Partial completions?

For a long running Work order below is the business scenario:

Costing Method : Actual Costing

Work Order Details

Finished Goods : 2 Each

Raw Material Required: 45 Feet

Work Order is completed in 2 Batch.

1. Partial Completion 1
   1. Finished Goods LOT A : 1 Nos
   2. Raw Material Consumed: 20 Feet (Cost 20*10= $200)
   3. Hence the Unit Cost For LOT A should be $200.
2. Completion No 2
   1. Finished Good LOT B: 1 Nos
   2. Raw Material Consumed: 25 Feet (Cost 25*10 = $250)
   3. Hence the unit cost For LOT B should be $250.

But Currently when the Provision Completions option is set as 'Value Using accumulated WIP balances'. After the work order is closed a WIP Adjustment entry is getting generated to update the cost of LOT A to $225, and the LOTB is also costed at $225.