Does adding freight lines to an already approved invoice change the WFStatus to NeedsReapproval?

Summary: We are updating the Invoice Approval Notification Template.

We have changed the title of the notification to say "Invoice Needs Reapproval" when the Workflow Status is Needs Reapproval.

I am under the impression that any change to the Invoice Amount will require the Invoice to be reapproved hence change the Workflow status to Needs Reapproval.

However when we add a Freight or Miscellaneous line it doesn't appear to change the approval status to Needs Reapproval.

How can we change the invoice status to Needs Reapproval?