Updating Studio Theme, using Studio Child

Hey Tammie-
Would you remind me what I need to do to my child theme when updating Studio Theme? I remember that I need to compare functions.php as per this thread: https://premium.wpmudev.org/forums/topic/new-child-theme-position-in-updated-themes#post-70401, but I do not remember if I use the latest function, css and other changes that may exist from the updated parent theme or the child that is within the updated parent?