Complex sentence: Rosalynn's father died of leukemia when she was 13, so she helped her mother raise her younger siblings, as well as assist in the dressmaking business in order to meet the family's financial obligations.
Split into simpler sentences: Rosalynn's father died of leukemia when she was 13. Thereafter she helped her mother raise her younger siblings, as well as assist in the dressmaking business in order to meet the family's financial obligations.