So Vorb.esp should be checked when rebuilding the Bashed Patch - and then removed? If so, I guess I have to add it back again each time I rebuild the patch?
You should delete the vorb.esp if you use a bashed patch with the modified posh.py
The wrye bash script attach the "Skel_" skeletons in "_male" folder to the NPCs every time you create a batched patch. If i release new skeletons you only have to delete the old "Skel_" files in the folder and copy the new ones into it. Then create a bashed patch. All Npcs will then use VORB. I also use a Wrye Bash to build the esp. All i do is rename it to VORB.esp

I have no experience with scripting an esp file, but i learned a bit python.