For reasons of functionality when a search is performed within a drop-down menu, can the option to create a non-existent value be added? and assign it to the menu after adding it, can you add this functionality automatically?
By checking the functionality, you can create values in the related table.
Such functionality is not available out-of-the-box. Indeed the component can be used as lookup editor (as we do) however adding records to related table will require multiple fields to be filled while DropDown component can work only with two properties - ValueProperty and TextProperty.