If that's the case then you probably could add the Ps. demasoni, however you may have to relocate the L. chisumulae, L. sp. "mbamba" and possibly the Cy. afra (which variant?).
You may want to try and stick with around five species in this tank, and keep them in groups. I wouldn't recommend M. auratus, they can be a real pain. They've sent more than few beginners packing up the hobby.
The Metriaclima callainos and Metriaclima greshakei should be fine with the Ps. demasoni. Some others to consider might be Labidochromis caeruleus, Pseudotropheus sp. "acei" and Melanochromis cyaneorhabdos. Groups of five or six of each would be best. Keep the Ps. demasoni to at least 12. The Victorian could probably stay, but I wouldn't be sure unless we know what it is. I can't comment on the hybrids as they really could be just about anything, with any sort of temperament.