Complex sentence: Other changes had to accommodate expansion of the roles of the Roman Proconsul, Sévère, and that of Félix, Pauline's father, whose character became a deep bass rather than a tenor.
Split into simpler sentences: Other changes had to accommodate expansion of the roles of the Roman Proconsul, Sévère, and that of Félix, Pauline's father. This latter role became a deep bass rather than a tenor.