SAP R/3 --> SAP PI --> Primavera Integration

Dear SAP Guru's,

We have a scenario where we need to integrate the SAP R/3 system with Primavera ( third party) using SAP PI.(synchronous call)

SAP R/3 is providing the RFC and

Primavera is giving a webservlet link.

Now R/3 system sending the BAPI data to SAP PI, PI sending the data to HTTP location.

In response Primavera is sending the response in xml .

I have created the data types and message types for both request and response for the Primavera system.

The problem is that the response structure of Primavera xml(which is generated from the weblink)  and the one we have created is different.

Please let me know how can I transform the response xml structure of Primavera to my response data type structure.

regards,