Question: is kylo ren darth caedus?
Answer: The problem is, Walt Disney and Lucasfilm has disregarded all the characters and stories of Star Wars Expanded Universe or Star Wars Legends, that's the reason why they never used the name "Jacen Solo or Darth Caedus" in the movie. But yes, Kylo Ren is equivalent to Darth Caedus in Star Wars EU.