We have had members do this in the past successfully, but the problem now, as @tgauchat mentions, is SuperLAN Connect, which will indeed keep adding any LAN – connected devices that it recognizes, such as a Phillips hue bridge, to both accounts. You can delete the devices after they’ve been added, but they will keep reappearing. It’s a big Account management issue in my opinion, such is for those who want to have an Airbnb space or a “mother-in-law” apartment or, as you mentioned, for teens. But at the present time there’s nothing you can do about it unless you also set up a separate ethernet connection.
If you only have zwave and zigbee devices, it shouldn’t be an issue.