You need to prevent her from going after your son. She has too much freedom. Teach her crate and X pen training. Leerburg has a good Xpen training video on Youtube.
At this age they can be annoying little monsters so you have to teach them. There is plenty of info when you go onto the search icon.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015