[Chimera-users] superimposing an all-atom structure to a reduced one

Dear all, I have two instances of the same protein. One is the original pdb structure which has been locally deformed and saved as the second pdb structure. I would like to match the 2 pdb structures. However, one structure is a reduced version of the other in that it contains only the carbon-alpha trace plus one or two atoms of the side chain. I get an error message when I use MatchMatcher. What can I do to superimpose the all-atom structure onto the reduced one? Many thanks for your help! Damien ps: I can join the two pdb structures if necessary