Complex sentence: Glazer appointed his sons, Joel Glazer, Avram Glazer and Bryan Glazer as Manchester United board members, to replace the vacancies of resigned board members, some of whom, like Sir Roy Gardner, resigned in protest.
Split into simpler sentences: Glazer appointed his sons, Joel Glazer, Avram Glazer and Bryan Glazer as Manchester United board members, to replace the vacancies of resigned board members. Some of them, like Sir Roy Gardner, resigned in protest.