Here are the resources that I will be using... Shape Viewer, Archibald and ConTEXT

Next I choose what I want to modify. In this case I want to modify a set of trailers to be from the same road and still be unique from the other trailers in the set. I also want to make a flat to carry them on.

I make a working directory outside of the sim. I copy the shape file, its textures and other related files to this working directory. I also copy one of the flat cars shapes and its related files. Here is a list:

I apply my naming convention to make them unique to the others in their original directory.