How to add a new WBS Element to Existing Project using BAPI_PROJECT_MAINTAIN?

Hi Friends,

     I have created a Project 'ABC' with WBS elements as like below

      ABC

        |____1

        |         |_1.1

        |         |_1.2

        |         |_1.3

         |____2

                  |_2.1

       Now i wanted to add a new WBS element(1.1.1) Under (1.1) using BAPI_PROJECT_MAINTAIN.

      So please give your suggestions to achieve this requirement.

Thanks,

Dinesh