Event on which Objects in Editor spawn into Map during Gameplay?

What i’m trying to achieve:

During regular editing I want to be able to place actors in the level and have them there on level load. Once the play session ends I take all actors that still exist and save them in a binary file. On next ‘play’ I load them and place them where they were on the previous play session (getting world object persistence).

However the originally placed actors in the editor also respawn so you end up with some duplicates etc.

So what I would like to know is which event in what class is responsible for spawning the actors that are saved in mapdata / editor - so that i can override that behaviour based on custom conditions?

I’ve solved this another way (through tracking of destroyed / picked up objects and saving the persistent paths of these into saved data - then cleaning them up on server start.)

Still am curious to see the answer if anyone knows though.