How to implement manual save system which involves multi level streaming?

Hi,I am trying to make a save system which involves manual save only which includes player inventory,player stats, level stats such as door unlocks, picked items, light on/off, enemy stats etc. However I use level streaming, which creates a problem when loading and unloading the streaming level i.e if i don’t manually save in that stream level if i load it again after unloading it whatever i have picked up like killed enemies or picked up items will spawn again. Currently a solution I think of is creating a separate temporary save for each streaming level saving automatically when unloading and reading from that the next time I stream the level. When saving manually , save all the level data and character data. This means if i have multiple streaming levels in a single persistent level I’d would have to save the data of all the streaming levels when manually saving.This-if I have a lot of streaming levels - seems to become tedious and consumes more memory. Is there a simple way to achieve this? Also in alien isolation even the pose of the enemy when saving is saved, can I achieve that? Thank you in advance.