Complex sentence: They use this to their advantage by switching their hairstyles and both performing as idols, but only underneath Ami's name, and the only people who know about it are the members of the 765 Production.
Split into simpler sentences: They use this to their advantage by switching their hairstyles and both performing as idols, but only underneath Ami's name. The only people who know about it are the members of the 765 Production.