How do replicate a Widget for all clients including the server

so i wanna do a multiplayer game but how can i replicate the Widget for all clients including the server ? What BP should i use and how can i do it?

You can use multicast or client function calls to tell clients when they should show a widget, but the widgets themselves do not replicate.

Yes but i’ve wanted to do a multicast in the GameMode but because the GM is server-based so i’m struggling a lot can you show me a blueprint representing what i wanna create?

Move your functions/variables from the game mode to the game state.
Game state is replicated to all clients and exists on the server.

I highly recommend that you check out the Free Network Compendium by eXi.