Complex sentence: On December 21,2009, the Rage organization announced its agreement with Major League Soccer's Philadelphia Union to become their official minor league affiliate, and re-branded as Reading United A.C. with immediate effect for the 2010 PDL season.
Split into simpler sentences: On December 21,2009, the Rage organization announced its agreement with Major League Soccer's Philadelphia Union to become their official minor league affiliate. The club was re-branded as Reading United A.C. with immediate effect for the 2010 PDL season.