What feature doesn't exist? I don't know what you mean. You can export a grouped and welded obj directly from Poser into your runtime via the file menu.

You can import a welded obj and send it to zbrush via goz and create morphs that way.

You can also send a rigged and posed figure to zbrush via goz, create jcms and any other kind of morph and send it back to poser.

The thing you can't do is work on the model of a rigged figure that's been saved to the library because Poser does not keep that model welded when saved. That's the version of the model that has the welding issue. But once you redirect the cr2 to the master (welded) obj that you manually exported via the file menu, you can then bring that model into poser and work on morphs.