rig the underlying figure.....do the plates on a separate layer, or as a second (clothing) figure, name them with the corresponding underlying body part...just like you would with clothing....and, that should be it,  You're wanting these rigged for use in Poser, right?  So if you do it this way, the body will be a regular body...use that cr2 for the armor...and conform them to the body.

What modelling app did you use?  Have you tried boning in that?