Add info to already populated InventJournalTrans

Hi!

I have created a on-hand InventJournalTrans - all lines is populated with my Items. Now i want to import what i counted from excel and add to the right linenum - corresponding with the right ItemNo.

I know the import function and looking for a way in the import criteria (data import/export) tab to change linenum so it will add the "counted" info to the right record.

Thank you.