The new dynamic XFA API of PDFKit.NET 5.0 allows populating and consuming dynamic XFA documents.
Static and dynamic XFA
PDFKit.NET 4.0 already supports static XFA forms. 5.0 adds support for dynamic XFA forms.
In a static form the form’s appearance and layout is fixed, regardless of the form data. Any unfilled fields are present in the form.
Dynamic forms can change in appearance in response to changes in the data or interaction such as clicking buttons. Dynamic forms may also be designed to change structure to accommodate changes in the structure of the data supplied to the form. For example, new table rows or new pages may be added if there is data for it. Another example is a field that resizes itself depending on its content.
Here is a typical example of a dynamic XFA form before and after filling. The highlighted parts show how rows are added and how content moves to the next page.