Negative Adjustment including Item Charge

hi, I would like to ask for guidance please.

I have created a new item to test the unit cost calculation, I've created and received 2 POs for the item. I've created another PO with a Charge Item and assigned to both previously created POs. my first question is, can the 'Expected Cost' of the Charge Item be included in the Average Cost Calculation of the Item? Cause it's only being taken into consideration once the PO is invoiced. Then I wanted to pass a negative adjustment but changed the Unit Cost to the actual cost of the item excluding the Charge Item allocation, but once I've ran the Adjust Cost Item Entries, NAV is adding another negative adjustment entry with a value which I'm not sure how it's being calculated. Can you please indicate which values is this being calculated on?

thanks in advance!