Una chica de opereta
A poor composer sells his songs to a music publisher who attributes them to his son, who sells them to a famous singer. Seeking the son, the musician's daughter will unexpectedly find a job as secretary to the singer, disguised as an unattractive and authoritative woman who effectively controls his careless lifestyle.
Starring Josita Hernán, Fernando Fernán Gómez, José Isbert, Lily Vincenti, Luis Prendes, Juan Moreno Rigo, José Sanchíz, Luis Pérez de León, Ana María Quijada, Enriqueta Villasiul
Watch "Una chica de opereta" on FlixOlè released in 1944. It's a comedy movie, and has a rating of 4.5 out of 10 from Imdb which is fairly low for this kind of movie.