@mylle BMW NAV VI only supports gpx file format 1.1 to get waypoints, so be sure to export or in this case "save as..." as the export tool last time I checked only allowed gpx 1.2.
Then when you have moved the file from PC to the navigator you import the track and then manually edit the soft blue waypoints you want into hard waypoints (orange flags).
(open travel planner, route, and change destinations, click on blue dots to change into orange flags)