I don't know how to edit your file, sorry. If you want, you can even make it so your in-game character is Cynthia. All you need is to replace some sprites.
^ the only issue (which for me is a deal breaker but dunno about others) is that Cynthia's sprites are gen 4 sprites and hence larger than all other sprites in Reborn (they're gen 3).
I can't edit saves either but if no one volunteers to do it, I can breed you the Pokémon you need
Oh, I'm just using the light skin female sprite. It looks almost exactly like a younger version of her, so. Also I can't ask you to do that, it'd be a lot harder to do for the team I have in mind (hidden abilities, availability etc). But, thank you though. I appreciate it!