I have a commissioned project. Here is what I am trying to do. I have a scene with 6 figures. 2 primary figures and 4 secondary. What I need to do is be able to have the four figures be invisible for a render .... and in another be the only figures so that they can be transparent overlays ... like ghosts. I know I can do this with two versions of the scene. But the problem is I want to be able to do this entirely in the original scene so I can compare different camera angles and still have all the figures line up properly. Is there a way to do this that isn't extremely time consuming?

Look up grouping objects in the Poser manual. You can assign one "layer" of characters to one grouping object, and another "layer" of characters to another grouping object and show or hide the visibility of the parent grouping object which will hide everything parented to it.

If the four "secondary" figures are to be see-through ghosts, you could make them refractive, and render the scene in one go. This material sampler is in freebies; it's a bit old, but I could update materials as needed.

Wow, both responses are wonderful. I think the second one may be my best bet for this commission. Thank you oh so much!!

In order to reduce the number of transmission bounces needed, if mouths are closed, set all of those interior parts to be completely (remember to zero out specular). For clothes, use the same setup as shown above, using the clothing's color map. Render with plenty of transmission samples and set transmission bounces high (32?) and the overall max bounces high (99?). The render engine will only use as many bounces as needed to complete a path from camera to light source.

Here's the ghost MAT set.

Thank you sooo much!!