Update Address of SalesOrder Partnerfunction

[helge23]

Hi, 

we are currently working on a migration to an S4 Hana System (onPromise).

To implement a special business process, I need to change an address of a partner(function) of an existing salesorder. 
With the old SAP ERP System I used the BAPI_SALESORDER_CHANGE for this. 
To familiarise myself with new tools, I would like to solve this with RAP. 
I have implemented i_salesordertp and can e.g. change the customer number of the partner.
But how can I change the address of theses customer / salesorder partner function?

Is it even possible?
Or how can I solve this alternatively?

Thanks and best regards,
Helge