Complex sentence: Alexander made cameo appearances in the second season of "Curb Your Enthusiasm", playing himself and appeared in the seventh season of "Curb Your Enthusiasm", along with the other three principal "Seinfeld" cast members.
Split into simpler sentences: Alexander made cameo appearances in the second season of "Curb Your Enthusiasm", playing himself. Alexander also appeared in the seventh season of "Curb Your Enthusiasm", along with the other three principal "Seinfeld" cast members.