Here my doubt is when there is a foreign key why the header_id value is not getting copied automatically to the Lines Table. In forms 6i If we have a foreign key defined it gets copied automatically. In OAF is this feature not available?
I see your perspective, but OAF is built on a separate architecture than forms and handling of many functionalities are different here. As far as I understand in OA Framework, whenever a row is created you need to write code to set the Primary Key (may be in Create method of EO or something else). Hope that clarifies.