Inventory System Widget Problem in multiplayer

When running a dedicated server, we want the item to
be added to slot 1 after each client gets the item as a line trace.
But now my game is not working. when Standalone is work.alt text
Could you please explain the server execution
and the owning client execution and multicast execution of custom events?
Please tell me how to fix it to work.

PlayerBP(Send PickUpItem) > Controller(Get It And Send It) > InventoryUI(Add The Item As Child)

Please tell me where i add custom event(Multi,Server,Client??) correctly.
Please tell me Replicate concept.