Basically, the situation is more complex. When you see "Hair" in the Dressing room, actually you're seeing both Hair and Cap model of that character combined together (or at least most characters; Humar has 10 "hair" but just one "cap" for the sunglasses; Huney has no "cap" at all, while androids only have "heads").
For example, a FOnewearl has "plIcap00.nj", "plIhai00.nj", "plIcap01.nj", "plIhai01.nj" and so on 'till "plIcap09.nj" and "plIhai09.nj" (the number of "hair.nj" and "cap.nj" goes from 00 to 09, while in the Dressing room they are labeled from 1 to 10).
What you are asking, if i am correct, is to take parts of a character "cap" 07 and load them in another position. It's not possible without 3d model editing to do such a thing (and this requires Blender and the trasposition of the finished work in the proper ".nj" format, all things i've never tried myself).
I mean, you can still swap a character "cap.nj" with another "cap.nj". It's quite easy, just copy the wanted "plcap.nj" or the "plhair.nj" present in "EphineaPSO/data" and then rename it like that one you want to swap; then you have to do the same work with hair/cap textures contained in plA/B/...Itex.afs (with TextureManager). The results may vary from: "Cool!", "Very cool!" and "What the hell is that?". Especially things get unpredictable when you swap cap or hair from a character class to another, because "head" size and texture's room varies.
In the end, it's all about trying...
