I don't think Transaction Pro lets you update invoices that already exist in QBO. If you export the invoices, update the info and try to re-import it, you get an error that those Invoice Numbers already exist. There doesn't seem to be a way to update/overwrite info that already exists in QBO from Transaction Pro. 

Have you actually done what you're suggesting? I feel like you're just schilling for them without actually trying out the solution.