[chimerax-users] Question about processing of multi-model PDB

Dear Chimera-X users ! I am working on the processing of a multi-model pdb file containing biological assembly of the dimeric protein. Precisely, every monomer is in a separate model with the same chain ID (A). I need to rename the chain A to chain B in the second model and then fuse the both models, so that the entire construction will be in the same model. What commands could be used to such modifications? Many thanks in advance Enrico