Complex sentence: He worked closely with his family in music especially his brother Eddy who assisted his younger brother create his early demos to present to record labels which led to EMI signing him up in 1999 at the age of 20.
Split into simpler sentences: He worked closely with his family in music, especially his brother Eddy, who assisted his younger brother to create his early demos. These were presented to record labels including EMI, who signed him in 1999 at the age of 20.