[Chimera-users] removing side chains

I have a session that someone has given me. It consists of 24 monomers in two states, each monomer colored differently. In the model panel I see only two IDs. I need to do a morph showing just the ribbons. Because the overall number of atoms is quite large, I want to strip off the side chains in order to reduce the computation. Is there an easy way to do this? Or do I have to go back to individual monomers, strip off the side chains, recolor, and recombine them, before morphing? thanks, Matt