Hi RAM,
the BAdI Implementation you could use is ADD_NEW_ELEMENT ( HRHAP00_ENHANCE_FRE1 ) .
You have to add this functionality to your PHAP form. Goto Categry group and make this BadI available. After that got to your form and select tab columns and select in the dropdown "free enhancement" the BadI you added before. After that you have to create a new node (VC element).
On the frontend you will get an Add Button. With that button you can add a new VC element on runtime.
If you wan to display the form in your portal you can use WD component HAP_MAIN_DOCUMENT to display the form. Before you have to check the configuration parameters.
br
Martin