To Attach Multiple References from a Single Directory

Click the Attach Reference icon ( Drawing > Attach > Reference ).
The Attach Reference dialog opens.
Select the DGN files that contain the models to attach as references.

Tip: To select multiple files, hold the <Ctrl> or <Shift> key as you select the files.
From the Attachment Method option menu, select Interactive.
Click Open.
The Reference Attachment Settings dialog opens for the first file in the selection list.
Modify the attachment settings, as required, then click OK.
The Reference Attachment Settings dialog opens for the next file in the selection list.
Modify the attachment settings, as required, for each subsequent reference in the list.