Vortex has the Rules feature to control load order. You can tell it to put a mod after another, such as the last mod.
If Mid-PlayThrough... never do anything other than put a new mod at the end of the load order, or replace an existing mod (for an update, unless the author said it wont work). You can't delete, or add anywhere other than at the end. See golden rule
Since loot is sorting behind the scenes, and its own rules are updating, its possible to get a new sort even if you change nothing. To eliminate that, you can turn off auto sort. Then if adding to the end, keep a record of the current order, so that you can be sure it does not change. You will need to manually hit the sort button, when you add your rule
You can't put an esm at the end, even if you think you did, skyrim will force it back up. This is why Toys needs a new game in all cases of introducing it to your Load Order
Yes this is hard, fragile, and unfortunately no mod manager is helping much. So you must manage it, and avoid changes in the first place.
This is how it has always been. This applies to all mods. People promoting a "clean save" procedure are perpetuating old myths that don't work as they straight up change the load order.
