Watching part two it was so obvious that Michael just didn't choose his boys, he chose their families. These two families were and are both so strange.
The mothers, the sister, the grandmother -- so many times they were smiling from the great memories. The Robsons, moving to the U.S., leaving a bipolar, depressed father who hungs himself when the last one left. None of them seemed all that sorry to me or is it their sorryness is mixed up gladness for everything they got out of it.
ETA: Only Wade's brother seemed grounded in reality and with a heavy heart and my heart went out to him since he was the last to leave for the U.S. and it was then the dad hung himself.
I was appalled at both families and that's why I think Michael chose his familes even more carefully than his kids. There's no other explanation. If someone has one or a different theory -- someone who actually watched both parts -- I'd be very interested to hear it.