I bought a half marathon and triathlon training plan from Training Peaks that one used to be able to upload the tcx file to Garmin Training Center, which would in turn upload to my Garmin watch. Now that training center isn't supported, does anyone know how to use Garmin Connect to upload a third party training plan so I can ultimately get it transferred to my watch?
As far as I can tell, this isn't something that you can do with Garmin Connect. You could manually reproduce the workout data and then arrange the workouts into a plan, but that is about it.