I would say absolutely no to a 35G Hex. If you keep more than one you keep 1 male, 3 females or more; no way is there enough lengthy in a 35 Hex to prevent them from killing each other and they would have no where near enough swimming space.
You could try a 30 long, but it still would not be ideal based on water volume. If you tried it it would have to be 1 male, and 3 females, nothing else in the tank, and you might end up with fry so you would have to have a plan for those. You would have to massively overfilter and commit to large water changes, probably minimum 50% weekly.
40 Long would be a sight more comfortable and you could have other Mbuna in there with them then.