Project Definition and PEP elements

Hello,

Project Definition

PEP Element 001

PEP Element 002

I am adding elements to the definition of PEP project. For this I am using the BAPI: BAPI_BUS2054_CREATE_MULTI.

How do I can do to make the item PEP 002, PEP hang hierarchically element 001 and not the definition of project?

Should I use another BAPI?

Thank you.