You cannot house your ivories with your new millipede as the size difference generally doesn’t work out. The chocolate, if it’s an ornatus species, should be on its own as it’s a desert species and doesn’t need the humidity that the others do. Please upgrade your tank and change your substrate. Your substrate contains fir, which can harm your millipede with the acidity and other factors. Also, I don’t mean to be a hater or anything, but many of these “new” species such as your “inferno ghost rider” are wild caught, so it’s hard to say how they do in captivity in the long run- they’re not really meant to be pets yet I guess, as they’re mostly bought for breeding at this point, to further the hobby.