Complex sentence: When the situation became intolerable, she was taken in by her maternal grandparents in Seattle, Augusta Morganstern, who was Jewish, and Harold Preston, a prominent attorney and co-founder of the law firm Preston Gates & Ellis, who was a Presbyterian.
Split into simpler sentences: When the situation became intolerable, she was taken in by her maternal grandparents in Seattle. Her maternal grandmother, Augusta Morganstern, was Jewish, and her maternal grandfather, Harold Preston, was a prominent attorney and co-founder of the law firm Preston Gates & Ellis, and was a Presbyterian.