In 2015, he made a guest appearance on the "Volume Three" album by Janne Stark's Mountain of Power. He sang on the tracks "Hey Serena/Wheel Of Fortune Turning". On the album Stark also covered Merryweather's songs "Give It Everything We Got/Kryptonite". The album was released on Grooveyard Records. This spawned further collaboration between them and, in 2016, they started working on an album under the name Merryweather Stark. The album "Carved in Rock" was released on CD and double vinyl by GMR Music in 2018.