GMLive applies to event that the live_call is called from - so, if you want to update changes in both parent's and child's step events, you'll need to add the snip in both of them. For slightly better understanding, GM events are essentially special scripts, and event_inherited simply calls the next script in inheritance chain, so having that live-updated (which, in turn, executes the new event code inside live_call()) does not have any effect on scripts/events that call it.