[CONNECT C#] Accessing Microstation App using MstnPlatformNET

Hi,

I'm trying to update some code and getting rid of  Bentley.Interop.MicroStationDGN namespace in order to fully switch to Bentley.MstnPlatformNET and Bentley.DgnPlatformNET.

I have an application which externally connects to Microstation and asks for some data from the active design file.

The new way to access the Application is Bentley.MstnPlatformNET.InteropServices.Utilities.ComApp.ActiveDesignFile.

However this gives me back a Bentley.Interop.MicroStationDGN.DesignFile , not a Bentley.DgnPlatformNET.DgnFile.

Is there a better way to access the Application that I'm missing? Or I cannot simply get rid of the older lib?

Thank you!