Batch update Sales Invoice, Receive money, Spend money

I want to add an entry (eg: xyz product = 10$) in 85 different invoices of the same company (eg: Star Exports) as i missed it previously for some reason. Now when I tried using batch update option and copied it in MS Office Excel I am just not able to figure out how to add this entry and update all 85 invoices.
It will be very helpful if some one can throw some light on the topic and guide me the way.

THANKS!!