When the service member’s duty station and TDY location are in different countries overseas, and the service member travels Space-A to CONUS, may they return Space- A to their duty station?

No. The service member must return Space-A from CONUS to the overseas TDY point or to a location other than the permanent duty station. He or she must return to the TDY point (at personal expense, if necessary, if Space-A travel is not possible to the TDY point) in order to complete travel to the permanent duty station in a TDY status.