It's only a room for more characters to place. If you really need a small army of characters that won't fit onto the campaign map, then you stash the extas ones into the Support Group. If party members are in the cabinet or part of a pirate team or part of a custom map they can't be moved to the support group or deleted. That's the only function.
Hey guys, i'll probably finish the (rough) eboot.elf translation this week.
I'd like to ask, again, everyone to start looking for people who can do a review/contextual translation of the file, to see if the things translated there make sense.
Or just check the names to see if they are compatible with the English version.
Next time i post it'll be the eboot.jce file containing the Japanese text+translation+some file offsets (from eboot.elf) for guidance.