Moving data between fields in DISCO is straightforward. First, export the relevant fields and documents from DISCO through a doc list export. Be sure to include in the search view the information you want to move.
Based on the field you want to update, review the Overlayable fields to determine whether you will need to export an Instance report or a Document report. If you are not sure, select the Instance Report.
Once you have the report, you can use it to update the fields in DISCO by performing a metadata overlay. Simply map the column containing the values you want to move to the field you wish to use going forwards.