According to this document https://stripe.com/docs/api/invoices/line_item regarding the Stripe (Invoice) Line Item object, InvoiceLineItems include both SubscriptionItems and InvoiceItems.
They recommend: For lines with type=invoiceitem, use the invoice_item field to reference or update the originating Invoice Item object.
I don't see that field available for mapping, although I do see SubscriptionItem. Can this be added so I can cross-reference to the Invoice Item (ii_) as needed from the InvoiceLineItem (il_) records? If I try to use both I end up with duplicates.