Founder and first chairman of the first Roma organization in Poland (1952–1955), the so-called Komitet Cygański (Gypsy Committee), which was later re-organized as the Wojewódzki Zarząd Stowarzyszenia Cyganów Osiadłych w Wałbrzychu (Provincial Board of the Association of Settled Gypsies in Wałbrzych). In 1955, the Committee was dissolved and Siwak moved to Tarnów, with his family. In 1963, he was a co-founder of the oldest active Roma association in Poland, the Cygańskie Stowarzyszenie Kulturalno-Społeczne “Nowe Życie” (“New Life” Socio-Cultural Gypsy Association), renamed in 1989, the Społeczno-Kulturalne Stowarzyszenie Romów w Tarnowie: Centrum Kultury Romów (Tarnów Socio-Cultural Roma Association: Roma Culture Center).