17 years doesn't seem very long.
It is minimum 20 years. After that they will be on licence for life. I thought younger people got time off their sentences because they were young? The James Bulger murderers got 10 years for instance. So 20 years is comparitively longer.
The whole thing is pretty mind boggling, I can get how someone can have a grudge that results in them murdering their parent, but killing their innocent sister? It isn't like they tried to get away with it so needed to kill the sister, they just hung around and waited to be arrested.
FWIW It didn't take very long to piece this together, so I am really not sure what good these court orders do.