Sadier wrote and sang the lyrics to the track "Quick Canal" by Atlas Sound on their album "Logos" (2009). She contributed vocals to "PartyIsntOver/Campfire/Bimmer" on the album "Wolf" (2013) by Tyler, the Creator, and "Summer Long" on the album "Alexandre" (2014) by Brazilian band Mombojó. She wrote the lyrics and was featured in "La Ballade" on the album "Something About April II" (2016) by Adrian Younge, and sang on the album "I'm Willing" (2016) by Marker Starling. In 2017, she appeared on the Deerhoof song "Come Down Here and Say That" from their album "Mountain Moves". In 2019 she appeared on the Mercury Rev album "Bobbie Gentry's The Delta Sweete Revisited" where she sang lead vocals on the track "Mornin' Glory". In 2020, she appeared as featured lead singer on two compositions by Chapman Stick virtuoso Michael Bernier, released on his third solo full-length release "The Beach Album".