Looking at the linked post, I notice that you're trying to create 4 NPCs whose personalities are 'similar' to game NPCs.
At this point, I'm unclear as to whether you're trying to replace game NPCs with other NPCs of your own creation, simply rename and respec existing NPCs, or introduce 4 completely new NPCs to the game.
Even though the last sounds like the most work, it probably would be the least.
If you're trying some combination of rename/replace, it's going to be a lot harder, because everyone in the game world will still refer to Imoen as Imoen. From the moment you leave Irenicus' dungeon, you're going to have everyone talking about Imoen. Gaelan Bayle will still say "Aye, Imoen, that be her name." Your friends will probably be saying "Imoen? I thought her name was Alicia." Unless your friend's name is Alicia and she's an engineer, in which case, she'll probably think you're a stalker. Relationship issues aside, you could modify the game dialogue so that everybody refers to her as Alicia instead, but that would just mean a lot more work for you, and far more complicated work than merely swapping out the name on the character sheet. Let's face it. Your average player doesn't open the character record all that often. One of the things many players look for in deciding whether or not a game is worthwhile is internal continuity. Glaring continuity gaps caused by you and your friends seeing the name "Alicia" when everyone else calls her "Imoen" are visible from a long way away.
People have discussed the possibility of reintroducing NPCs killed in Irenicus' dungeon for years. Bring back Khalid/Dynaheir. One of the things that stops them is the amount of work involved. The game world thinks they're dead. To resurrect them, you'd have to change every instance where somebody mourns the loss of Khalid/Dynaheir. Though personally, I think it would be funny to have Khalid interject with "I got better!" To date, there has only been one successful
NPC resurrection: Jastey's Ajantis mod. Ajantis was the paladin you could recruit in
BG1. You accidentally kill him in the Windspear Hills. That's the only time in the entire game that Ajantis is mentioned, and even that mod hit a couple snags.
If it were me, and I was trying to impress my friends with the coolness of the game, I'd probably opt to write up a kind of one-day
NPC, someone the party could interact with in some way, or maybe even recruit. You could even name her Alicia and make her an engineer, if you wanted.