Can a DoD Secret clearance be converted to a DoS Secret clearance?

First you must have a final secret SSBI and the supporting unclassified message for Marines it's announced as ALMAR message and put in the training jacket or filed in S1 office. A final secret is required for all NATO secret so if you have no access to them type of documents or any comsec stuff you do not have a final secret clearance. Prior clearances stay with you, but only active when you have a need to know and proper forms or investigation done after 5 or 10 years after your discharged.