Complex sentence: Johannes became head of the family in 1650 when he was 25 years old, allthough the States-General of the Netherlands decided in the same year he was allowed to call himself "patroon" of Rensselaerswijck, but without any legal power.
Split into simpler sentences: Johannes became head of the family in 1650 when he was 25 years old. The States-General of the Netherlands decided he was allowed to call himself "patroon" of Rensselaerswijck, but without any legal power.