Thanks for this answer! Perfect timing, as I am just about to start implementing something that this issue would have affected. 
So the “Parent: Begin Play” blueprint node is actually a no-op in this case?
To me it seems that this behavior is a bit counter-intuitive and feels like going against what is standard in object-oriented programming (execution starts from the child’s overriding implementation, which is then responsible for calling the parent’s implementation). Of course, this is how it has to be in this case, but I think it would be good to document this behavior somewhere? Maybe here:
Exposing Gameplay Elements to Blueprints Visual Scripting in Unreal Engine | Unreal Engine Documentation → BlueprintNativeEvent