Complex sentence: After Erika's birth came that of her brother Klaus, with whom she was personally close her entire life--they went about "like twins", and Klaus Mann described their closeness as follows: "our solidarity was absolute and without reservation".
Split into simpler sentences: After Erika's birth came that of her brother Klaus, with whom she was personally close her entire life. They went about "like twins", and Klaus Mann described their closeness as follows: "our solidarity was absolute and without reservation".