Complex sentence: He had seven siblings but one had died in the womb, all of whom survived to adulthood, except for Hannah, the miscarriage, joined the family between Allen's birth in 1738 and 1751.
Split into simpler sentences: He had seven siblings but one had died in the womb, all of whom survived to adulthood, except for Hannah, the miscarriage. They joined the family between Allen's birth in 1738 and 1751.