Synchronous publishing in Ignition Gazebo in PreUpdate?

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I'm writing an Ignition Gazebo model plugin and I'd like to command multiple joint controllers from the plugin. The joint controllers provide a cmd_pos topic on which they can be commanded. If I publish to these topics in my plugin's PreUpdate phase, can I be sure that all these messages will be delivered before the PostUpdate phase of the same simulation step begins? At least when running a non-distributed simulation on one machine? Or what is the suggested method of synchronous control when the controllers I'm using do not react to any simulator events but only topics?