Sorry to necro-post, but I was curious to see who could be brought to the Greenhill Rescue Mission if all characters were recruited. Used the code to recruit all characters, including McDohl and Millie 2. Turned off all codes except the code to increase available limit from 81 to 83 (otherwise McDohl and Millie 2 would vanish). Here are the characters the game will let you bring. (Note: If you leave the codes on, the entire roster will show up.)
* = Characters you can't have at this point.
# = You can have this character if you abused the Matilda Glitch earlier.
! = Characters that will never appear in party select menu unless certain codes are used.
Besides the obvious last four characters it's just Sheena, Futch, and Ayda. Makes me wonder if something was changed late in development. As in, maybe the Greenhill Rescue Mission was moved to a different point in the plot as was previously envisioned. Very interesting, though. I always wondered about this ever since I brought Futch with me and he actually had lines.