Dedicated Server Workflow in Editor

We are working on an online multiplayer game based on a dedicated server.

We are struggling with finding the correct playmode settings for testing the MainMenu (offline) to Game Map (online/on the server) connection flow from the editor.
In the settings it allows us to launch a server in a different process and have the editor play as a standalone game, which then can connect to this server.
But starting with more than one client at a time behaves odd. The first client (in Editor) is correctly starting in the main menu map, whereas the second client (launched in a standalone window) starts on the game map.

Ideally we would want to be able to test the MainMenu->GameMap flow from the editor with multiple clients that all start from the MainMenu and connect to the server from there. We dont want to package the game every time just for testing this. Is there a way to achieve this?

What is the common workflow for testing such a server setup?