Nope, not possible with the current tools. You cannot edit either their 3d models and skill/personality, only their portraits (e.g. swap Pavle and Roman portrait so Pavle is now Roman but that's not exactly what you asked for xD)

well that sucks.. picture swapping sadly won't do it for me :/
Thanks tho

I rarely saw a mod tool so badly design, I cant mod the only things that I think is useful to mod like caracters stats or backpack slots.

If you look in Archetypes config you can edit some of the character stats, but most characters' archetype are missing.

Dweller_Generic affects Bruno, Marin, Emilia, Marko, Christo, Adem, Anja, Ruben and all the workshop civilians, while Adam and Esma have their own archetype, meaning you can change them however you want (except their "unique" skill).

For example you can make Adam a fast runner like Pavle and give him godlike combat ability and hp. Not so great but it's still something fun to try.