Would have been nice if marshmallow allowed you to pass only & partial into the top-level schema and have it passed down to the nested schemas. Would avoid needing to do this manually.
Doesn't look like it does right now, but from looking it might in the future. Lets revisit if they implement any of those options.
Both marshmallow-code/marshmallow#302 and marshmallow-code/marshmallow#151 look helpful.