How to place sub-lelevs in level streaming?

[Texn0krat]

Good evening. Can you please explain me how should I organize sub-levels in level’s panel? For example I have this structure of final map:

Red lines are doors, so from level 1 I can only go to level 2.
1 level is persistent and always loaded.
Should level 2 be sub-level to level 1?
Should levels 3,4,5,6,7,8 be subs to level 2?
Or how should it be?

[ClockworkOcean]

The sublevels can only be loaded in the persistent level. You can’t have nested sublevels.

[Texn0krat]

Oh, I thought it’s for loading organization…