Complex sentence: In 1973, his father founded the Christian Democratic Appeal (CDA) which was the senior party in the Dutch government for most of the period 1977-2010 and served as the President of the Dutch Senate in the period 1983-1991.
Split into simpler sentences: In 1973, his father founded the Christian Democratic Appeal (CDA) which was the senior party in the Dutch government for most of the period 1977-2010. His father also served as the President of the Dutch Senate in the period 1983-1991.