How does Warframe implement matchmaking without level travel?

Warframe uses P2P connections, I do too using OSS EOS lobbies.

Here is the scenario:
You are in your orbiter as a host, and you set the match to public. You start matchmaking and other players join your lobby. When they join you, they are still in their orbiters, and they do not see each other until the new map is loaded.

I can’t achieve the same results in Unreal Engine because:

  • the players must stay in their orbiters when connected to the host
  • the players must not see each other until moved to the new map
  • and it is not seamless (no hiccups)

How can I implement this? Can players join the host without traveling to the host’s map?