Complex sentence: When it was sold Rodriquez became a member of the supervisory board and worked as a boardmember until 2003, in that year the board was converted into an advisory board that Rodriquez joined.
Split into simpler sentences: When it was sold, Rodriquez became a member of the supervisory board and worked as a board member until 2003. In that year, the board was converted into an advisory board, which Rodriquez joined.