Depending if you've made the plates as seperate objects (plate1, plate2, plate3) etc you have two options. You can either plug them into one of the clothing items and see if that works, or you can try parenting the top plate to the collar and then using "point at" to get the other plate to follow the shoulder (upper arm). This doesn't always work and is reliant on how you've constructed the model. Another method which is a bit more trouble some would be to import all three plates, parent the first one to the collar and leave it static, import the second and third ones together, parent plate2 to plate1 and plate 3 to plate 2, then set plate2 to "point at" plate 3, and plate3 to "pointat" the shoulder. Again, this is dependant on how the props are created and is also reliant on you editing their centre's of rotation in Poser so they twist and slide appropriately. Dunno if that helps you. Alternatively you could do as JeffH suggests and learn all about the remote control, ECM/ERC/JCM and the other wonderful toys that people have discovered and work around it that way.