Rebate Agreement against Payer (HeadOffice)

Dear Experts,

I have a scenario where one of my customer is having several branches and one head office. I customer master against each branch customer we have maintained the main customer number in Head office field and sort key as '004'.

The head office acts as the payer where as branch customers are maintained as Bill to Party.

We need to create a rebate against the head office so that when ever a new SO is created against any of the branch customer the rebate agreement should flow.

Please let me know what should be configuration changes to be made.

Thanks

Ranjit Simon