Vally married Karl Weigl in 1921, and after the National Socialists took power in Austria in 1938, the couple emigrated with their son to the U.S. with assistance from the Quaker Society of Friends. In New York, Weigl worked as a music teacher and composer, and a grant from the National Endowment for the Arts allowed her to compose and record "Natures Moods", "New England Suite", and four song cycles. After receiving a master's degree at Columbia University, she also worked as a music therapist and became chief medical therapist at New York Medical College. She also taught at Roosevelt Cerebral Palsy School. Vally directed research projects at Mount Sinai Hospital's psychiatric division and the Hebrew Home for the Aged, and in the 1950s published a number of articles in the field of musical therapy. She died in New York City in 1982.