I made a new 'lydia' (CK 1.5), and liked the spells and perks I imbued in her, but wanted a sultry red-head... Enter eola. So, I modified eola, new hair, she gained some weight... And I then did a 'copy stack' from lydia's spells and perks to eola's.

Fine. I then made a new Skyrim install, placed Eola into it... And eventually, when I got to the end of Dragon Rising, there was lydia... My modified lydia. Her .esp was not in this game, but there she was. All I can assume is that copying the stacks of spells and perks somehow also copied her other characteristics, ALL of them, and tacked them onto eola, such that they invisibly tagged along until lydia showed up.

If anyone can explain this, or better yet tell me what I did wrong I'll be eternally grateful. (Well, not eternally, but you get the drift...)

If no one can explain this, then I guess I was the lucky person to find a 'gotcha'.

Sounds like save file bleed or something. I had a similar problem with a mod i made for Uthgerd .
never did really solve it until a new game.

...But, you see, I actually made a separate skyrim install just for this new character, and the modified lydia showed up uninvited, so to speak. Only npc.esp file included was eola's.

Did a bit of a test today. took a new skrim install, new creature kit, copied my eola.esp (made from my lydia.esp's spell and perks list) into the new skyrim. Opened up creature kit, made me a new jordis.esp file, then opened up a new object window, with that object window opened up my eola file, and copied the spell and perk lists to jordis.esp. Saved my new jordis, closed everything and deleted my eola.esp. Opened creature kit back up, opened Lydia, original lydia. opened eola, my modified (but deleted from the folder) eola.

So, it does appear that if you use the 'copy stack' feature from the SpellList tab, you take all of the copied-from npc's characteristics into your new.esp file, and thence into whatever game that you use that npc. But at least you don't take the copied-from's copied-from, ie in my case I didn't get the modified lydia that was also hiding in eola copied into jordis as well, just the eola bits. Whew. Confused? What I just proved to myself was that using the copystack feature only carried the actual characteristics of the copied-from, not the original donor, and also not the first and second donor. So Jordis only carried Eola's characteristics, not Lydia's, and not Lydia's AND eola's, into a new game with only Jordis.esp.

Now for someone to come up with a way to copy JUST the information that I want to use... Until then, I'll have to consider the copystack feature to be broken. (Sorry, Beth., give me a train and I'll try to make it fly... )