[Chimera-users] PDB post-processing

Dear Chimera users! After some post-processing of MD simulation I have extracted from the trajectory several snapshots as individual pdbs which I need to 1- to re-assign information regarding chain letters (which was lost after some operations on pdbs) for all of those structures assuming that within each of these pdbs residues are ordered correctly e.g from (1-104 which should be chain A) than from 1-100 (it should be chain B), than 1-70 (in should be chain C) etc. 2- superimpose and combine all of the pdbs within one model in nmr-like format. Thanks for help!