Complex sentence: Big Time Rush is an American pop singing group that formed in 2009, consisting of him, along with three other members, which are Kendall Schmidt, Carlos Pena, Jr., and Logan Henderson, all on vocals.
Split into simpler sentences: Big Time Rush is an American pop singing group that formed in 2009. The other three members are Kendall Schmidt, Carlos Pena, Jr., and Logan Henderson, all on vocals.