Marketing Budget using Bw-BPS & PS

Hello Gurus

We are Implementing Top_down Budgeting solution Via SAP CRM using BW-BPS & PS. We needed some help in integration.

When Budget is planned at Marketing plan & hierarchy  level it goes in BW system & a Project/WBS is created in PS.

Now point here is that budget should be committed through BW & available in ECC (PS). This is where we are not clear as to how this work.

we referred to a couple to links & blog like

Marketing Planning and Budgeting (SAP Library - SAP Brand Management)

Please help us understand the link between BW & ECC for Budget transfer

Regards

Rohit