Thanks again for the reply.
I assume once I create any Function Import in a service then only I can see DEFINE_ACTIONS method in MPC_EXT otherwise not (because right now I cannot). Also if it's so then this would be called for all the function imports in the service and we need to maintain a constant for a particular function import name and then code for that particular parameter name in that function import to make it optional. Also it may break if we have the same parameter name in multiple function imports of same service.
Thoughts?
BR