Member of Sunny Side relationship based on the text "Williams then played fiddle with Ed McKinney’s West Plains band, Sunny Side Up, and took part in sessions and programs with the McKinney band right up to the end of his life." from https://mofiddledance.org/2020/01/roger-williams-missouri-bluegrass-fiddler-dies-at-84/. I'm unsure if "member of" or "supporting artist for" is more accurate.