Bulk Editing Multiple Invoices with Overwriting at time of upload

Bulk Editing Multiple Invoices with Overwriting at time of upload

Hello,

I would like to edit a few 100 invoices. Only the HSN needs to be updated. When I am trying to upload the excel sheet with the data updated, I get an error: The Invoices are skipped as they already exist.
I know the invoices exist but I would only like to change the HSN for all the Invoices. The invoices have multiple products and with several different HSNs. It took several hours to manually update in the excel sheet. However now I am not able to upload it into Zoho Books.
Please help.