What is the best way to make Vicks and Wedge into "normal" party members?

I've played around a bit with the ASM hacking, and I was able to get as far as changing the events so that, after encountering Tritoch, you find yourself standing in front of the Beginner's House in Narshe with Vicks and Wedge, and without Terra. That part was actually pretty easy.

But it seems that Wedge and Vicks are not equippable, and I've read that the game has a lot of strangeness with the way the 13th and 14th slots work, often replacing them with ghosts, Moogles, or other guest characters.

So would I be better off overwriting two other characters in the game with Vicks and Wedge, or trying to make the existing Vicks and Wedge equippable and such?

The first route would involve hacking several earlier events in the game, and the initially assigned party, to include the "new" Vicks and Wedge rather than the original ones, and figuring out a way to change the palettes used for them outside of battle. The second route seems like it would be more difficult, and require me to change the way the airship and shops deal with party members.

I won't be using Locke, Sabin, or Cyan in this hack, so I would have no problem overwriting them.

While I'm at it, I was also thinking of giving Vicks a green uniform while leaving Wedge brown, so as to establish one of them as higher ranking and also help differentiate them in battle. Not sure if that would be difficult or not.

Okay, so this is a conversation which has come up a lot on these forums, and the short answer is that you need to replace one of your existing party members. Gogo and Umaro are characters with some interesting/annoying additional properties and exceptions, but with some ASM hacking you can adjust them so they act like any other character.

Replace a character from the playable character list with the soldier sprite. You may lose them but you at least get Vicks or Wedge in the game.

Long Answer:
Well, I am helping work on the ASM for the 15th Man project, which will eventually add a full character to the roster. If we are successful, putting Wedge/Vicks in the cast without replacing existing characters *should* be doable. If you intend to keep the Soldier sprites for them, it may even be trivial. We are still pretty early in the process but so far there is nothing foreseeable that will totally block us from adding 1-2 new characters. There are still some questions as far as unique magic lists and whatnot, but there are partial solutions for even these that are less-than-ideal, but functional. It's just a matter of putting in the work. When the 15th Man project is finished, there will be a patch for adding them, plus I will probably make a detailed tutorial on how to do it yourself... expanding the ROM with FF3usme will be a requirement.

Short Answer:
Play my upcoming hack.