Complex sentence: Although Iwama style practitioners remained part of the Aikikai until Saito's death in 2002, followers of Saito subsequently split into two groups; one remaining with the Aikikai and the other forming the independent Shinshin Aikishuren Kai in 2004 around Saito's son Hitohiro Saito.
Split into simpler sentences: Although Iwama style practitioners remained part of the Aikikai until Saito's death in 2002, followers of Saito subsequently split into two groups. One remained with the Aikikai and the other formed the independent Shinshin Aikishuren Kai in 2004 around Saito's son Hitohiro Saito.