There have been at least two groups named Supersister, the most famous one being a Dutch progressive rock band from the 1970s. The other one is a British girl group. 1. Supersister was an experimental rock band from The Hague, The Netherlands, that existed from 1968 to 1974. They played a jazz-tinged brand of progressive rock. Classic line-up: Robert Jan Stips (keyboards, vocals), Sacha van Geest (flute), Marco Vrolijk (drums) and Ron van Eck (bass).