Join two or more MARC files into one

Open MarcEdit 

Open the Tools Menu from the main window

Open the MARC Processing Tools option, then select MARCJoin

Select the Save File icon to choose a location and name for your joined MARC file, then select the Save button to enter the file path in the Save File field in the MARCJoin window

Click on the File(s) to Join icon to select the MARC files you would like to join, then select Open to add the file paths to the correct field in the MARCJoin window

Select the Process button. A confirmation alert will pop up telling you the files have been combined to the file specified as the save file.