Yes, indeed, your search should reveal quite a large number of unccounted for soldiers. For some time I have been amazed at how there is always more to find out about the Civil War, given that it has already received so much attention. Even though it is by far the most researched topic in American history, there is still much to learn.
On a totally unrelated note, did you get the pdf I sent you awhile back? I think it was probably during your email "blackout."