Complex sentence: In 2008, SUEZ itself then merged with Gaz de France to form GDF SUEZ-and Tractebel Engineering became, overnight, the engineering consultancy for the world's no.1 independent energy Group.
Split into simpler sentences: In 2008, SUEZ itself then merged with Gaz de France to form GDF SUEZ. Thus, Tractebel Engineering became the engineering consultancy for the world's leading independent energy Group.