Hi Vicky,
if the DDIC search help has this restriction logic (e.g. if the import parameter COUNTRY has value 'US' it only provides the US states for REGION results) and it is assigned correctly with these parameters to the DDIC structure, you don't need to do anything in the feeder class. This is done automatically by the Web Dynpro F4 processor, and it would work the same way with a freestyle WD component if the DDIC structure is attached to the relevant context node.
Regards, Jens