For the pending documentation:
=== doc_core_api (4.5) ===

Chapter: Table Configuration Array, $TCA
Part: ['columns'][fieldname]['config'] / TYPE: "inline"

Field: appeareance:
newRecordPosition (string)
Values: 'top', 'bottom, auto' - default: 'bottom'
Defines where the new record is inserted in the list of records. 
If set to auto, the position of the link seth with "levelLinksPosition" to create the new relation is taken into account.