Thats true. I've also noticed that where the character data is in assembly, there is what I think is empty space. Perhaps someone with more knowledge could verify this? It might be possible to add the data for Sephiroth and Y.Cloud there. And also, I found another #LOUD (cloud) entry before the initial #LOUD (cloud) entry with the character ID and stats. Anybody know what that is?
Sephiroth Character ID, stats, some other stuff. 128 bytes long.
http://imageshack.us/f/508/sephirothcoding.png/The opcode for this address is changed when the character ID is Vincent's. That's the only difference I've seen so far. As you've said before, the stats do change automatically when he is added to the party but not when I change their Character ID's and when that happens only that character is enabled.
http://imageshack.us/f/16/vincentchangesassemblyo.png/Young Cloud Character ID, stats, some other stuff. 128 bytes long.
http://imageshack.us/f/36/youngclouddata.png/Cait Sith changes the opcode for the same address on Character ID slot. Everything else remains unchanged.
http://imageshack.us/f/849/caitsithchangesopcode.png/Cloud Character ID,stats, who knows what else @_@. 128 bytes long.
http://imageshack.us/f/803/clouddata.png/Cloud excess data or instructions??? 88 bytes long.
http://imageshack.us/f/713/clouddataextramaybe.png/Edit: This part seems to change with what I'm currently doing/where I'm currently at in the game. It may be an event flag. Also, some changes occur when I am in the Title Screen and choose "Continue" while the PSX is loading the memory card.
Empty Data Space after character definitions??? A little bit over 600 bytes.
http://imageshack.us/f/163/emptydataspace.png/Edit: Below this is the memory of the Items in inventory.
All of these include the opcode along with the memory region highlighted so that you may perhaps understand a little more of what I'm talking about. Hope this helps somewhat.
I'd like to help more on changing the stuff on the discs itself but I've had no experience in that before. Sorry for my ignorance on that last post about the .TIM files. I should have read the posts linking to information about file types in the FF7 disc first before posting. Hope this information helps.