Complex sentence: With her sisters, Martha and Helvetia "Vet" Boswell, she performed in the 1930s as The Boswell Sisters and became a highly influential singing group during this period via recordings and radio.
Split into simpler sentences: With her sisters, Martha and Helvetia "Vet" Boswell, she performed in the 1930s as The Boswell Sisters. They became a highly influential singing group during this period via recordings and radio.