MOST of the time, all actions in the same tier are resolved simultaneously. Multi-kills can be thought of as taking place in public (A goes to kill C, is killed by B on his way to leave C's house). Roleblockers blocking each other isn't a problem, roleblockers blocking roleblockers who block other roles gets a little Schrödinger...
(which is one reason never to have more than one roleblocker)
.Texas Justice, I would think, would handle simul-kills just fine, considering the showdown mentality inherent in the scenario...