What you are doing is a pretty good way to end up with a corrupted save. If you had an .esp loaded that added a new item to game, that item would have a FormID comprised of that.esp assigned slot, and relative ID within the .esp. An instance of such item in your inventory would be referenced by that FormID, written to your save game. If you move that item entry to another .esp, it will be in a different slot, and likely get assigned a different relative ID. In other words, it will have new FormID, and old one will no longer be there. So what happens when you try to load a save and it has FormIDs not referencing something valid? Best case, you'll be missing stuff. Items may be gone from inventory, Follower might go missing, or your follower pretty hairdo might go ugly vanilla. Worst case, you get a crash. Lets say you just end up missing stuff. Thing is, those dangling references are still in your save, polluting it. They can bite you in the rear a couple hundred gameplay hours later. Flagging an esp as esl has about same effect as moving its entries to another .esp. FormIDs will be different and those already referenced in a save will go undefined. Not an issue starting a new game, but merging or esl-flagging mods midgame is asking for trouble. At the very least what you should do: 1. Unequip any items from mods you plan to merge, and prefferably dump them into a chest you don't use often. Any new custom added followers should be dismissed, reset if using AFT. 2. Disable all the mods you plan to merge or ESL-flag. Load your save, do nothing for a minute or so, save again and exit. 3. Use Fallrim Tools ReSaver to clean your save. Enable the new merged/flagged mod(s).