Complex sentence: When Hamelech David passed away, Yosef Yitzchak was two and Sultana, his wife was pregnant, so Yosef Yitzchak had a younger sister who was two years younger, and they both went to Israel.
Split into simpler sentences: When Hamelech David passed away, Yosef Yitzchak was two and Sultana, Hamelech David's wife was pregnant. Thus, Yosef Yitzchak had a younger sister who was two years younger, and they both travelled to Israel.