Hi everyone,
I've been learning rom hacking in general in the past few weeks. When it comes to changing monster sprites, FF3SE is a great tool. Sadly, there is not much empty space for new monster sprites.
So I decided to move the monsters graphics to the empty F1 bank of a expanded rom. I changed the value of what I think is the starting offset of monsters graphics (at C1/210F, C1/2115 and C1/211B) in what I think is the corresponding subroutine that load a monster graphic. (I might be totally offtrack...)
I have two questions:
1)
Do I have to change the location of the Monster 8-High Composition Data and 16-High Composition Data as well or the unused 220 byte (starting at D2B424) would be used if I add more sprites via FF3SE? I downloaded the source code of FF3SE and changed the value of the variable "offset" in the respective loading and saving functions. I also increased the value of the variable "maxTileNumber" so that way I could have more space for monster sprites in the editor. The code however doesn't compile. I have an error saying some header file is missing (png.h I think).
I sent a email to the creator of the editor but I haven't receive an answer(yet).
2) Have anyone ever tried that process? If so, am I on the right track or am I missing some steps? 
I've been studying programming since last year but never learned C++ (the language FF3SE is coded in) specifically. As for assembly, I'm learning but I don't know enough to understand every line of the subroutines that loads the monster graphic, mold, composition data, x and y position. Is it a harder process than I think to move the monsters graphics and being able to use FF3SE after that?
I hope someone can help, this site has been a good ressource for answering my questions so far.