File Export Wavefront Obj. Or use the obj from Geometries that your .pp2 references (if you are not using embedded geometry) as an import into your external modeler. In general, unless there is a specific reason, you want your export to be in a default zero state.
If exporting from a Poser scene it's probably best to leave all options unchecked unless there's a specific reason you want the groups/materials to be used in your external modeler. For selection purposes would be a good reason. In general you do not need this information for creation of a morph target for a static prop. Props do not have body parts per se, but that's jumping ahead a bit.
Import your prop Obj into your modeler. You might have to scale your Obj up to work comfortably, be certain to scale back to default scale after you make your edits and are taking it back to Poser. Poser scale is very small compared to most other 3d apps.
Make whatever edits you need to. Be careful to not translate/move the entire model while editing unless you specifically need to do so for the intended morph. Do not increase the poly count of the Obj, do not add or delete vertices, or make any cuts or welds. Doing so will cause the wrong number of vertices error or change the winding/vertex order, rendering your morph target useless.
With your prop loaded in a scene back in poser, go to the props properties located in parameters and click load morph target. Select your edited mesh that you exported from your modeler. Name/label your morph if necessary, you might have named your exported/edited mesh as the relevant morph name when you exported it from your modeler, if so your morph will inherit that name so renaming will be unnecessary.
A morph dial will appear, with your selected label, in the props parameters. Dial to 1. If everything went ok your prop will deform to whatever morph you created.

Rinse and repeat. This is just the basic workflow. Should get you started...

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Forum: Poser - OFFICIAL

Subject: Morphing prop