Complex sentence: The TSSG was established in 1996 by Willie Donnelly, Eamonn de Leastar and Mícheál Ó Foghlú, and they were joined by Barry Downes to form the executive team.
Split into simpler sentences: The TSSG was established in 1996 by Willie Donnelly and Eamonn de Leastar. They were joined later by Mícheál Ó Foghlú and Barry Downes to form the executive team.