I have 2 Garmin devices (vívoactive HR and eTrex Touch 35) which I use to track my activities simultaneously. I need to use both because eTrex has problem with average heart rate and intensive minutes are not accumulated. On the other hand the problems don't occur on vivoactive, but eTrex has bigger screen which is great on bike.
So, I would like to track activities on two devices, save it, but upload only from one device (vivoactive). I found auto upload option in Garmin Connect app for eTrex device, but unfortunately it is disabled, so I can't change them. Why? See attached screenshot ('Autoprzesyłanie' means auto upload in Polish).