Dim id As AcDb.ObjectId
Using db2 As New AcDb.Database(False, False)
    'Add the block by loading it from the source file.
    db2.ReadDwgFile(FileName, IO.FileShare.Read, True, Nothing)
    Dim bt2 As AcDb.BlockTable = manager.GetObject(db2.BlockTableId, AcDb.OpenMode.ForRead)
    If bt2.Has(BlockName) Then
        'Use the default mapping to "wblock" the table from the source to the destination.
        db2.WblockCloneObjects(New AcDb.ObjectIdCollection(New AcDb.ObjectId() {bt2(BlockName)}), db.BlockTableId, New AcDb.IdMapping(), AcDb.DuplicateRecordCloning.Replace, False)
    Else    'Create a block from the source file's existing modelspace entities.
        id = db.Insert(BlockName, db2, False)
    End If
End Using