Complex sentence: Henrietta Waddy joined the group in 1947 after Willa Ward retired; she added a rougher alto and the enthusiastic stage manners taken from her South Carolina church background.
Split into simpler sentences: Henrietta Waddy joined the group in 1947, after Willa Ward retired. Waddy brought to the group a "rougher" alto sound and the enthusiastic stage manners learned from her South Carolina church background.