For what reason does the US client need to see the address of the supplier of his vendor?
Is there any relationship?
Where does he need to see this UK address?
with the current information I would say there is no such process and setup in SAP.
You can have a partner in your vendor master and the purchase order e.g. GS goods supplier to show that the goods come from somewhere else than China.
you could as well use the UK vendor as vendor and the China vendor just as OA Order address.
All this is possible with partner functions, Please have a look into the docu in help.sap.com and available content in SCN.