I just watched the movie Parkland on Amazon Prime and it featured the brother quite a bit. Good movie.
I read the book. It was good. I've been looking for the movie. Glad to know it's finally on Amazon Prime and I can add it to my queue. I remember the brother came across as a decent person. Their mother, on the other hand, was a real piece of work.
Oswald's Russian wife, Marina still lives in Dallas, long ago remarried and became a U.S. citizen, and believes to this day that Lee had nothing to do with killing the President.