How can I bulk update sales documents to delete specific line items and add new line items? Using a saved search to export the data and an import, I know how to add new line items, but can't figure out how to entirely delete (not zero out) specific line items entirely from the sales document. Is it possible?

You'd have to use "overwrite sublists" and upload exactly what you want to have on the order- I'd warn that this is very dangerous.

@KevinJ of Kansas When overwriting sublists, do you have to use the "add" or "add or update" option or can you just use the "update" option? When doing this method, do you use the InternalID for the transaction as the identifying field, it will wipe out all lines for that transaction, and then replace them with the item level internalids that you put on the upload file?

I would suggest only using update. Your summary is correct - note that you'll need to duplicate all fields that are populated in order to only add "additional" lines, because you're going to recreate the lines.