[wildfly-dev] best way to get extensions to apply model changes immediately at runtime?

I'm in the need to support runtime changes to my subsystem extension (for example, someone should be able to use the CLI to add a child resource or change a resource's attribute and have those changes take effect immediately - i.e. support Flag.RESTART_NONE rather than Flag.RESTART_RESOURCE_SERVICES). I'm assuming I need to do this in the AddStepHandler but I'm confused if I should override AbstractAddStepHandler.populateModel or AbstractAddStepHandler.performRuntime. Can someone fill me in on which one is recommended to be used? I'm not sure under which conditions each of those should be used and why. The other thing is, it seems this is only for adding child resources (or removing them; I assume it is analogous for Remove Step Handlers). How do you intercept the changing of an attribute value for an existing resource, particularly if my resource extends PersistentResourceDefinition? Thanks for any help, John Mazz