Multiple snakes out at once??

[Bogertophis]

Craig, this is my opinion only, no real experience.
I would feel comfortable with the Borneo and Ball together. The King snake on the other hand might try to eat the others? They go after Rattlesnakes in the wild.

Oh, NEVER with king snakes...I agree, they are ophiophagus (snake eaters). Some others (similar kinds like milk snakes, longnose snakes) are too, though smaller
and less risk. Indigo snakes too...and cobras (hopefully you would NOT be letting any cobras out to roam, lol).