Buffer stock from supplier

Question: We purchase Product A from Supplier 100 pcs $22/piece (total $2200). We also get buffer stock of Product A (10 pcs $0/piece) from the same supplier. How do we create Supplier Invoice so the COGS per piece is $20?

Because in real contract, we just purchase 100 pcs. 10 pcs Buffer Stocks must be excluded from $2200.

NB: $2200 / 110 pcs =  $20

Answer: In company's accounting poilicy, in the Inventory valuation method field, the only supported values are as follows:

- Weighted average
- FIFO

https://kb.1ci.com/1C_Drive/Guides/1C_Drive_User_Guide/Setting_up_business_processes/Setting_up_accounting_policy/Specifying_finance_settings/

Alternatively, you can register goods upon receipt separately: to another warehouse, to another batch, or to another variant.