Complex sentence: Theodor Schieder, who headed it, Peter Rassow, Hans Rothfels, and later also Werner Conze--together with archivist Adolf Diestelkamp and international law expert Rudolf Laun.
Split into simpler sentences: Theodor Schieder, who headed it, Peter Rassow, Hans Rothfels, and later also Werner Conze. The other members were archivist Adolf Diestelkamp and international law expert Rudolf Laun.