DD214s are never altered or changed once issued. However, you can have a DD215 issued – which is used for corrections and additions to your DD214. This can usually be done by application to the National Personnel Records Center, or your Branch’s Board of Corrections. If you record supports it, the NPRC can usually do this faster. Submit copies of your supporting documentation (never send originals). You can start here: http://www.touchstoneresearchgroup.com/reference/dd0149.pdf