Final Fantasy IV DS hacking help

[Ghost XIII]

I doubt anyone on this board would be able to assist you with this, I don't know how much time people spend here trying to mod FFIV DS. There are character change codes out there, I think I found them on the gamefaqs forum before. However, I think character abilities are tied to sprite in that game so even if you regain child Rydia you will very likely be stuck with minimal summoning and black magic and her paltry selections of white magic spells. She also will be able to use staffs, but not whips.