CRPro to the rescue.
Just merge all textures and geometries each in one directory, run CRPro to fix any incorrect references (there will be many but normally it fixes them without asking questions.
This will change all refrence to include a full path, so everybody knows where to find things (of course when you save anything with Poser (any version) it will change the references in the saved files back to relative references).
Once you have gone through everything with CRPro, you can run it again and again without any problems to fix anything Poser might have screwed up.
On a big set of content it can take a long time to run CRPro (a really long time the first time you run it). It will find all kinds of problems (and fix most of them).