When do an update in Inventory accounts in Master Inventory Organization affects accounting?

Hello,

The accounting manager deactivated some account combination because some internal accounting validation rules, and those account combination are part of the accounts assigned in the master inventory organization. We have a problem because when the user try to create a new item in inventory the system send a message like this 'The combination account is disabled. Please select another one'.

I was reviewing and the option is do the update in the accounts in master inventory organization. These are the accounts that need to be modified: Expense Account, Purchase Variance Account, Invoice Price Variance Account, Cost of Good Sold Account and Cost Variance Account. I did the change in my test instance; I can change all the accounts combinations except 'Cost Variance Account' because is greyed out against update. I am sendin the details in the document attached. Please see: MST Inventory Org.Account.docx