How can add I my Custom TDS.tiw to the available drop down list . (Survey-File -Import -Field book)
Place the TIW file in the location with the other files. The default location is C:\Program Files\Bentley\OpenRoads Designer CONNECT Edition\OpenRoadsDesigner\Default\SurveyFiles\Data
Then open the Survey Settings Properties from the Explorer
Expand the Data File parsing section and open the Data Import Items dialog by clicking the three dots.
Then click the Add Row icon to add a row to the bottom of the Items list
Then fill out the row and in the FormatFile column select and browse to your TIW file.
It should now appear in the list when you go to import
You can do this operation in the DGNLIB where you store your survey settings so that it will always be available.