I did something similar. Collecting all blueprints and even their Functions, so i could have a fully customizable/moddable platform.
Maybe
SearchFilter.bRecursiveClasses = true;
will help you.
But you have to remove
SearchFilter.ClassNames.Add(UBlueprint::StaticClass()->GetFName()); SearchFilter.ClassNames.Add(UBlueprintGeneratedClass::StaticClass()->GetFName());
then. PS: for the forum maintainers: the new editor sucks big time when you copy/paste code. (running firefox 55.0.3)