Complex sentence: However, he is despised by Aunt Marion (Sylvia Sidney), who favors Mark and thinks Damien a bad influence, even threatening to cut Richard out of her will if he does not separate the two boys.
Split into simpler sentences: However, he is despised by Aunt Marion (Sylvia Sidney), who favors Mark and thinks Damien a bad influence. Marion even threatens to cut Richard out of her will if he does not separate the two boys.