To Attach the Active Model to Itself as a Reference (Self-Reference)

In the References dialog ( Drawing > Attach > References dialog launcher ), click the Attach Reference icon.

The Attach Reference dialog opens.
Select the open DGN file and click Open.
From the Model option menu, select the active model.
(Optional) Type in a logical name and description.
Do one of the following:

Attach the model as a coincident reference to itself.

or
Attach using a saved view or named boundary.

Note: The user preference Edit Self References determines whether models that are attached to themselves (self-attached) are automatically updated to reflect modifications to the active model. Edit Self References is on by default. This makes it easier to use self-attached references, for example, to generate drawings of 3D models.