I know how to turn all of these things into a combined prop without using that script.

1 First export your main figure... name the obj file, upon export, something that will identify it in the hierarchy.

File export wavefront obj

Check these boxes: Include Existing Groups in Polygon Groups, and Preserve Existing Material Names.

Export

2 Now Reimport and check these boxes only: Weld Identical Vertices.

Repeat for additional parented or conformed figures. Each their own export/import with the settings in step1 and 2

Once you have all of your elements exported/reimported/welded and together export the whole lot with the settings I gave in step one and reimport with all checkboxes unchecked.

Everything should be a single object now, uvs are retained, and the poly groups are there but welded at former part divisions. You'll have to reapply materials so I'd save mat files in preparation. Also there might be some numbering attached to material or poly groups, but for your purposes it doesn't really matter

Let me know if you run into any snags.

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