Thank you for your help! My keywork script now looks like yours. I checked the input file and it looks like that part IDs for the two linebodies are just 1 and 2, so I kept the 1 under "surfa". I noticed that *SECTION_BEAM and *MAT_CABLE_DISCRETE_BEAM are already in the input k file -- so I'm guessing it's sufficient to use the section tool in the GUI to assign the cable setting to the two bodies?

One issue I notice when I run this keywork script: I get run-away energy conservation errors. What might be causing this? When I stopped the solve, the bottom string seems to ride up and to the left of the top string, with one of the loops (yellow) going through the top (teal). It seems like not all the contact instances are accounted for. For context: the vertices of the top string are fixed and axial forces are applied along the bottom strings.