SKYRIMSE Adding mods mid-playthrough

[elenhil]

Hi guys!

 

I wonder what's the general opinion on adding mods mid-playthrough - that is, changing the load order/? I often read that you should never ever change a mod's position in load order midgame (which, I suppose, is inevitable unless you place the mod dead last), but I didn't care to research the logic behind it. Is it applicable to all mod types, or are the specific mod types that are sensitive to this?

[Greg]

This is going by what I seem to remember of the issue with Skyrim Legendary Edition so it's subject to being incorrect and missing important details.
 
The save file contains a list of plugin names and position in the load order like this:
 

00 Skyrim.esm
01 Update.esm
02 Dawnguard.esm
03 Hearthfires.esm
04 Dragonborn.esm
05 Unofficial Skyrim Special Edition Patch.esp
...

Also note that the first byte of all FormIds stored in the save file contains the plugin's load order (e.g. 03003035 for Iron Fittings in Hearthfires.esm). If the load order of a plugin changes when a save file is loaded, the game must build a new plugin load order set (like the one shown above) and update all FormIds in the save file to the new order order index. If you swap Dawnguard.esm and Hearthfires.esm for example, Iron Inogts has to change from 03003035 to 02003035. The game must do this for every FormId in the save file (and there are a lot of them) and there is some risk this may break some scripts that are stored in the save file. I don't know what the game does with scripts, but I imagine it has to do something since these are generally tied to specific plugins as well.

 

This probably isn't relevant for your specific case, but if the plugin names do not match exactly (or a plugin is removed from the load order), all FormIds for the old plugin slot are removed from the save. This means if you uncheck Hearthfires.esm and load an existing save, all the Hearthfire items in your inventory and containers are gone. The save files already on disk are not changed, but any new saves will no longer have any Hearthfire items.