Adding Espers?

Is there a way to add new espers? In my hack Kefka will not be present but I would like him to be somewhat of an easter egg as an Esper and to be the most powerful (obviously not accessable unless you beat a specific boss or something). But I don't know if I really want to replace any espers. How would I go about this? READY TO LEARN!!!!

Espers are spells 53 to 80. There is only 255 (0xFF) possible spells, and they are all taken. You would need to sacrifice a spell and also, you would have to expand the data related to the spells that espers teach and squeeze and extra esper sprite.

I'm not 100% sure if I'm missing something because I've never attempted that.

Edit: I also foresee code to edit in bank C2. It's likely that last esper ID is hardcoded in one or many places.

Only way you'd be able to "add" an Esper is to replace one that already exists in memory, in my hack, my main character's father is a dragon and and as an Esper he essentially replaces Maduin, Terra's father[/align]. So I find a nifty dragon monster sprite and replace it with Maduin's.

I see. So more work would be required to add. Then I'll think of something to replace it with. Gonna try really hard to make it epic so it's worthy of Kefka xD