Caesar, Tiberius or Octavian, Claudius or any combination thereof for the boys and Aurelia or Julia for the girl. Only names of Roman patricians, Emperors and other historical legendary Generals/Kings and Queens are worthy to be carried by beasts as majestic as cats, like Wellington, Napoleon, Nelson, Katherine, Elizabeth.
Or you can always go the other route, naming them Mittens and shit, but then be prepared for their terrible vengeance driven by anger and frustration.