Mary,

You may want to check with the National Cemetery to see if they will let you set a stone there. If the soldier's burial location is UNKNOWN at the cemetery, I do not know if they will allow you to set what is essentially a "memorial stone" at a National Cemetery. Private Cemeteries do it all the time but I believe it provides following generations a false identification of an ancestor because these "memorial stones" are little different than actually stones. You really need to check with that National Cemetery.

Respectfully,

Gerald D. Hodge, Jr.
War Between the States Historian
Historian: 39th Georgia Volunteer Infantry Regiment
http://39thGAVOLINFRGT.homestead.com/39thHomepage.html