So you loaded the Inventory and the GL balances is for Jan. 31st and with no transaction to date.
You could reverse out the number from Jan. 31st and import the new balances. This would be easier from an audit trail versus entering in the change in the balances.
When you load the inventory - put in a negative quantity adjust for the change.
For the GL balances - enter in a credit to reverse a debit and a debit to reverse a credit.