xserve/xraid volume mounting and sharing question

In setting up an xserve/xraid I've gotten the following request. The xraid has been partioned into four volumes. We want to be ale to mount one volume, then have the others accessable as directories from the mounted volume. We do not wish to make people mount all four volumes to access all files. Is there a way to do this? We tried symbolic links, but those links don't work when logging in via afp.