I agree with DarkEdge that it is probably best to have the earrings as smart props. When Poser refuses to save something as a smart prop it is because you have used "Select Subset" when saving the prop. If you need to use "Select Subset" to include two or more objects in a pp2 (prop) file, then you will need to edit the pp2 to turn it into a smart prop. Open the pp2 in a text editor. Search for any lines that begin with "parent", edit these lines to use "smartparent" and the name of the parent actor, eg:

smartparent head

If the earrings were made up of multiple objects, eg a ring and a pendant parented to the ring, then you would only only need to smartparent the ring part to the head.