In my organization, we have local chapters who sometimes get part of the national membership dues. The BOD doesn't want the breakdown to show up on the email receipt, and the calculation has to be done whether the dues are posted online or offline, so I do my breakdown during the posting of the line item for the membership dues.
I access the chapter share and reduce the line item by the chapter's share and create a new line item for the chapters share, since it's a different financial type. Everything works well, except the chapter's share doesn't show up on the bookkeeping report. That's when I noticed that the Financial Item record isn't created for the chapter's share line item record.
So I looked at the API explorer and I can't figure out which API entity and which API call creates the Financial Item records.