Bobby Laird showed me a homo-tetramer with chains A, B, C, D that when morphed between two states with the Chimera morph conformations tool swapped two of the monomers. In other words the 4 chains from one state weren't correctly paired with the 4 chains from the other state so two monomers exchanged positions during the morph. The tetramers were built from dimers 1pfk and 2pfk by using the symmetry of the unit cell with other software (coot?). How does morph conformations decide which chains to pair? Tom