As a freelancer, Daum wrote more than 3000 orchestrations and worked with numerous artists in all genres, varying from crossover and outright classical music to German folk music and with artists such as Vicky Leandros, Karel Gott, Demis Roussos, and Die Jungen Tenöre.
For instance she was a judge along with Demis Roussos at the Miss World final of 1976 held in London where Cindy Breakespeare was crowned Miss World.
The Greek government released the accomplice, Ali Atwa, and in exchange the hijackers released eight Greek citizens, including Greek pop singer Demis Roussos.
Leandros composed and produced for many other artists such as Julio Iglesias, Demis Roussos, Nana Mouskouri, Jairo, among others.
The English version of "Mamy Blue" has also been recorded by Horace Andy, Julio Iglesias, Vicky Leandros, Genya Ravan, Demis Roussos, Muslim Magomayev and Laima Vaikule; Nicoletta also recorded the English version in addition to the French.