Try setting configuration variable MS_GEOXFM_DISALLOW_INFERRED_DBCONNECTION=1.
If this variable is set to any value then no attempt is made to infer a database connection from the design files in the session.
By default, XFM will attempt to infer a database connection if no database connection is specified in the XFM schema. During file open, XFM looks for a database control element in the masterfile and if found, will use the connection string in the element for ODBC and OLEDB database server types and otherwise use MicroStation's DB connection manager to request that the user connect to the database. If no DB control element is found, then XFM will use MicroStation's DB connection manager to request that the user connect to the database when the first element with a database linkage is encountered.
If the user chooses not to connect to the database when requested or disconnects during a session, then XFM will not allow tools to read or write features in the session.
Regards,
Chris