Of course they're also suffering in Hell. As to whether they have some inverted diabolical hierarchy, it would be different from a normal hierarchy. Souls of the damned are all in non serviam mode, so if they weren't going to serve God, they're not about to become subordinate to Satan either, unless they're forced to by God, so it's probably more of a chaotic free-for-all. If forced by God to be subordinate (mirroring the order that they had before they fell), this would undoubtedly be contributing to their torments.