Create Steam Session Two Overlap

Using Steam Multiplayer Sessions

Is it impossible to open the first session, implement multi, and open another session within that session?

There is no problem until implementing multi by opening the first session, but if I try to open another session in it, it does not open.

​To summarize
session open → go to level1 ->(in level1)session2 open[this part has trouble] → go to level2

Did you stop it on Steam?

To destroy a session, use : ISteamMatchmaking::LeaveLobby

When there is no user in a session, the session is destroyed.
Source : Steam Matchmaking & Lobbies (Steamworks Documentation)