On returning to Copenhagen in 1914, she opened a ballet and rhythmic dance school for children and young adults.
Her own courses developed from a foundation in classical ballet to far more expressive choreography based on trends in modern dance.
[1] The school she opened in 1927 (Danserindeskolen) was very special in that it not only taught dance with special attention to anatomy, Mensendieck gymnastics, history of dance, music, costumes and scenography, but covered the normal school curriculum with Danish, German, French, English, maths, geography and cultural history.
For her attention to French language and culture, Mollerup was awarded the Ordre des Palmes Académiques.
Among its students were the actress Lilian Ellis, the dancers Bodil Genkel and Else Knipschildt, and the ballerina Nini Theilade.